Decimal Fractions

decimal fractions

Step by Step solutions of Concise Mathematics ICSE Class-7 Maths chapter 4- Decimal Fractions by Selina is provided.

Table Of Contents
  1. Q1: Convert the following into fractions in their lowest terms:
  2. Q2: Convert into decimal fractions:
  3. Q3: Write the number of decimal places in:
  4. Q4: Write the following decimals as word statements:
  5. Q5: Convert the given fractions into like fractions:
  6. Q1: Add:
  7. Q2: Subtract the first number from the second:
  8. Q3: Simplify:
  9. Q4: Find the difference between 6.85 and 0.685.
  10. Q5: Take out the sum of 19.38 and 56.025 from 200.111.
  11. Q6: Add 13.95 and 1.003, and from the result, subtract the sum of 2.794 and 6.2.
  12. Q7: What should be added to 39.587 to give 80.375?
  13. Q8: What should be subtracted from 100 to give 19.29?
  14. Q9: What is excess of 584.29 over 213.95?
  15. Q10: Evaluate:
  16. Q11: What is the excess of 75 over 48.29?
  17. Q12: If A = 237.98 and B = 83.47. Find:
  18. Q13: The cost of one kg of sugar increases from ₹28.47 to ₹32.65. Find the increase in cost.
  19. Q1: Multiply:
  20. Q2: Multiply each number by 10, 100 and 1000:
  21. Q3: Evaluate:
  22. Q4: Divide:
  23. Q5: Divide each of given numbers by 10, 100, 1000 and 10000:
  24. Q6: Evaluate:
  25. Q7: Evaluate:
  26. Q8: Evaluate:
  27. Q9: Find the cost of 36.75 kg wheat at rate of ₹12.80 per kg.
  28. Q10: The cost of a pen is ₹56.15. Find the cost of 16 such pens.
  29. Q11: Evaluate
  30. Q12: Fifteen identical articles weigh 31.50 kg. Find the weigh of each article.
  31. Q13: The product of two numbers is 211.2. If one of these two numbers is 16.5, find the other number.
  32. Q14: One dozen identical articles cost ₹45.96. Find the cost of each article.
  33. Q15: Find whether the given division forms a terminating or a non-terminating decimal:
  34. Q1: The weight of an object is 306 kg. Find the total weight of 48 similar objects.
  35. Q2: Find the cost of 17.5m cloth at the rate of ₹112.50 per metre.
  36. Q3: One kilogram of oil costs ₹73.40. Find the cost of ₹9.75 kilograms of the oil.
  37. Q4: Total weight of 8 identical objects is 51.2 kg. Find the weight of each object.
  38. Q5: 18.5 m of oil costs ₹ 666. Find the cost of 3.8 m cloth.
  39. Q6: Find the value of:
  40. Q7: Evaluate:
  41. Q1: Which is greater: 5.038 or 5.3?
  42. Q2: Shyama bought 5 kg 300 g apples and 3 kg 250 g mangoes. Saria bought 4 kg 800 g oranges and 4 kg 150 g bananas. Who bought more fruits?
  43. Q3: Two kg of milk contains 0.315 kg of cream. The cream in 20 kg milk is:
  44. Q4: The distance walked by a boy is 86.4 km in 4.8 hours. The distance covered by him in one hour is:
  45. Q5: The number seven and 7 thousandth is:
  46. Q6: (56.56div1.4) is equal to:
  47. Q7: (left(2+frac{1}{2}right)divfrac{3}{5}) is equal to:
  48. Q8: Total cost of two pens at ₹5.30 each and four notebooks at ₹20.50 each is:
  49. Q9: (2.5+3.8div0.02) is equal to:
  50. Q10: By what decimal number should 0.0001 be divided to get 0.01?
  51. Q11: (3frac{1}{5}timesleft(frac{1}{2}+frac{3}{8}right)divfrac{21}{40}) is equal to:
  52. Q12: 5.80, 0.95, 1.87 and 1.92 in descending order are:
  53. Q13: (3-frac{1}{4} of left(15.8-3right)) is equal to:
  54. Q14: Statement 1: (0.05=0.050=0.005=0.00500) Statement 2: Any number of zeros put at the end (i.e. on the right side) of a decimal number does not change its value. Which of the following options is correct?
  55. Q15: Assertion (A): Representation of 6.25 as a vulgar fraction is (6frac{1}{4}). Reason (R): A fraction is said to be a vulgar fraction if the denominator is a whole number but not of the form ({10}^n, nin N).
  56. Q16: Assertion (A): If the product of two decimal numbers is 17.55 and one of them is 6.5, then other one is 2.7. Reason (R): In division of decimal numbers, the dividend is always exactly divisible and no remainder is left after certain steps. Also quotient is always reduced to a terminating decimal.
  57. Q17: Assertion (A): (3.10divleft(0.1times0.1right)=3.1). Reason (R): In division of a decimal number by ({10}^n, nin N), shift the decimal point to the right by as many digits equivalent to n in the power of 10 in the divisor.
  58. Q18: Assertion (A): 9, 9.56, 9.2, 9.005 are all unlike decimals, hence addition operations can't be performed. Reason (R): A whole number can also be expressed as a decimal number by putting a decimal after its unit's digit and after it as many zeroes required to perform addition operations with other like or unlike decimal numbers.

Exercise: 4-C

Q1: Multiply:

i. \(0.87 \times 10\)

Step 1: Multiply \(0.87\) by \(10\) (shift decimal 1 place right): \[ 0.87 \times 10 = 8.7 \] Answer: 8.7

ii. \(2.948 \times 100\)

Step 1: Multiply \(2.948\) by \(100\) (shift decimal 2 places right): \[ 2.948 \times 100 = 294.8 \] Answer: 294.8

iii. \(6.4 \times 1000\)

Step 1: Multiply \(6.4\) by \(1000\) (shift decimal 3 places right): \[ 6.4 \times 1000 = 6400 \] Answer: 6400

iv. \(5.8 \times 4\)

Step 1: Multiply \(5.8\) by \(4\):

5.8
× 4
────
 23.2

Answer: 23.2

v. \(16.32 \times 28\)

Step 1: Multiply \(16.32\) by \(28\):

 16.32
  × 28
────────
 130.56     (16.32 × 8)
 326.40    (16.32 × 20)
────────
 456.96

Answer: 456.96

vi. \(5.037 \times 8\)

Step 1: Multiply \(5.037\) by \(8\):

 5.037
 ×   8
───────
40.296

Answer: 40.296

vii. \(4.6 \times 2.1\)

Step 1: Remove decimals and multiply \(46 \times 21\):

   46
 × 21
  ─────
   46   (46 × 1)
  920   (46 × 20)
  ─────
  966

Step 2: Place decimal back (1 + 1 = 2 decimal places): \[ 4.6 \times 2.1 = 9.66 \] Answer: 9.66

viii. \(0.568 \times 6.4\)

Step 1: Remove decimals and multiply \(568 \times 64\):

  568
  ×64
 ──────
  2272   (568 × 4)
 34080   (568 × 60)
 ──────
 36352

Step 2: Place decimal back (3 + 1 = 4 decimal places): \[ 0.568 \times 6.4 = 3.6352 \] Answer: 3.6352


Q2: Multiply each number by 10, 100 and 1000:

i. \(0.5\)

\[ 0.5 \times 10 = 5.0 \\ 0.5 \times 100 = 50.0 \\ 0.5 \times 1000 = 500.0 \] Answer:5, 50, 500

ii. \(0.112\)

\[ 0.112 \times 10 = 1.12 \\ 0.112 \times 100 = 11.2 \\ 0.112 \times 1000 = 112.0 \] Answer:1.12, 11.2, 112

iii. \(4.8\)

\[ 4.8 \times 10 = 48.0 \\ 4.8 \times 100 = 480.0 \\ 4.8 \times 1000 = 4800.0 \] Answer:48, 480, 4800

iv. \(0.0359\)

\[ 0.0359 \times 10 = 0.359 \\ 0.0359 \times 100 = 3.59 \\ 0.0359 \times 1000 = 35.9 \] Answer:0.359, 3.59, 35.9

v. \(16.27\)

\[ 16.27 \times 10 = 162.7 \\ 16.27 \times 100 = 1627.0 \\ 16.27 \times 1000 = 16270.0 \] Answer:162.7, 1627, 16270

vi. \(234.8\)

\[ 234.8 \times 10 = 2348.0 \\ 234.8 \times 100 = 23480.0 \\ 234.8 \times 1000 = 234800.0 \] Answer:2348, 23480, 234800


Q3: Evaluate:

i. \(5.897 \times 2.3\)

Step 1: Remove decimals and multiply \(5897 \times 23\):

   5897
   × 23
 ──────
  17691   (5897 × 3)
 117940   (5897 × 20)
 ──────
 135631

Step 2: Place decimal back (3 + 1 = 4 decimal places): \[ 5.897 \times 2.3 = 13.5631 \] Answer:13.5631

ii. \(0.894 \times 87\)

Step 1: Remove decimals and multiply \(894 \times 87\):

   894
  × 87
 ─────
  6258   (894 × 7)
 71520   (894 × 80)
 ─────
 77778

Step 2: Place decimal back (3 decimal places): \[ 0.894 \times 87 = 77.778 \] Answer:77.778

iii. \(0.01 \times 0.001\)

Step 1: Remove decimals and multiply \(1 \times 1 = 1\):

  1
× 1
 ───
  1

Step 2: Place decimal back (2 + 3 = 5 decimal places): \[ 0.01 \times 0.001 = 0.00001 \] Answer:0.00001

iv. \(0.84 \times 2.2 \times 4\)

Step 1: Multiply \(0.84 \times 2.2\) Remove decimals and multiply \(84 \times 22\):

  84
× 22
────
 168   (84 × 2)
1680   (84 × 20)
────
1848

Place decimal back (2 decimal places total): \[ 0.84 \times 2.2 = 1.848 \]Step 2: Multiply \(1.848 \times 4\)

 1848
  × 4
─────
 7392

Place decimal back (3 decimal places): \[ 1.848 \times 4 = 7.392 \] Answer:7.392

v. \(4.75 \times 0.08 \times 3\)

Step 1: Multiply \(4.75 \times 0.08\) Remove decimals and multiply \(475 \times 8\):

 475
  ×8
────
3800

Place decimal back (4 decimal places total): \[ 4.75 \times 0.08 = 0.38 \]Step 2: Multiply \(0.38 \times 3\)
Remove decimals and multiply \(38 \times 3\):

 38
× 3
 ──
114

Place decimal back (2 decimal places): \[ 0.38 \times 3 = 1.14 \] Answer:1.14

vi. \(2.4 \times 3.5 \times 4.8\)

Step 1: Multiply \(2.4 \times 3.5\)
Remove decimals and multiply \(24 \times 35\):

  24
× 35
────
 120   (24 × 5)
 720   (24 × 30)
────
 840

Place decimal back (2 decimal places): \[ 2.4 \times 3.5 = 8.4 \]Step 2: Multiply \(8.4 \times 4.8\)
Remove decimals and multiply \(84 \times 48\):

  84
× 48
────
 672   (84 × 8)
3360   (84 × 40)
────
4032

Place decimal back (2 decimal places): \[ 8.4 \times 4.8 = 40.32 \] Answer:40.32

vii. \(0.8 \times 1.2 \times 0.25\)

Step 1: Multiply \(0.8 \times 1.2\)
Remove decimals and multiply \(8 \times 12\):

 12
× 8
 ──
 96

Place decimal back (2 decimal places): \[ 0.8 \times 1.2 = 0.96 \]Step 2: Multiply \(0.96 \times 0.25\)
Remove decimals and multiply \(96 \times 25\):

  96
× 25
────
 480 (96 × 5)
1920 (96 × 20)
────
2400

Place decimal back (4 decimal places): \[ 0.96 \times 0.25 = 0.24 \] Answer:0.24

viii. \(0.3 \times 0.03 \times 0.003\)

Step 1: Multiply \(0.3 \times 0.03\)
Remove decimals and multiply \(3 \times 3\):

  3
× 3
  ──
  9

Place decimal back (3 decimal places): \[ 0.3 \times 0.03 = 0.009 \]Step 2: Multiply \(0.009 \times 0.003\)
Remove decimals and multiply \(9 \times 3\):

  9
× 3
 ──
 27

Place decimal back (6 decimal places): \[ 0.009 \times 0.003 = 0.000027 \] Answer:0.000027


Q4: Divide:

i. \(54.9 \div 10\)

Step 1: Dividing by 10 shifts decimal point 1 place left: \[ 54.9 \div 10 = 5.49 \] Answer:5.49

ii. \(7.8 \div 100\)

Step 1: Dividing by 100 shifts decimal point 2 places left: \[ 7.8 \div 100 = 0.078 \] Answer:0.078

iii. \(324.76 \div 1000\)

Step 1: Dividing by 1000 shifts decimal point 3 places left: \[ 324.76 \div 1000 = 0.32476 \] Answer:0.32476

iv. \(12.8 \div 4\)

Step 1: Divide 12.8 by 4 using long division:

   3.2
  _____
4| 12.8
  -12
   ---
    08
    -8
    ---
     0

Answer:3.2

v. \(27.918 \div 9\)

Step 1: Divide 27.918 by 9 using long division:

   3.102
  _______
9| 27.918
  -27
   ----
    09
    -9
    ---
     01
      0
     ---
      18
     -18
     ---
       0

(Here 9 goes into 27 three times, remainder 0; next digit 9 goes 1 time; etc.) Answer:3.102

vi. \(4.672 \div 8\)

Step 1: Divide 4.672 by 8 using long division:

   0.584
  ______
8| 4.672
  -0
  ---
   46
  -40
   ---
    67
   -64
    ---
     32
    -32
     ---
      0

Answer:0.584

vii. \(4.32 \div 1.2\)

Step 1: Remove decimal from divisor by multiplying numerator and denominator by 10: \[ \frac{4.32}{1.2} = \frac{4.32 \times 10}{1.2 \times 10} = \frac{43.2}{12} \]Step 2: Divide 43.2 by 12 using long division:

    3.6
   _____
12| 43.2
   -36
   ---
     72
    -72
     ---
      0

Answer:3.6

viii. \(7.644 \div 1.4\)

Step 1: Remove decimal from divisor by multiplying numerator and denominator by 10: \[ \frac{7.644}{1.4} = \frac{7.644 \times 10}{1.4 \times 10} = \frac{76.44}{14} \]Step 2: Divide 76.44 by 14 using long division:

    5.46
   ______
14| 76.44
   -70
    ---
     64
    -56
     ---
      84
     -84
      ---
       0

Answer:5.46

ix. \(4.8432 \div 0.08\)

Step 1: Remove decimal from divisor by multiplying numerator and denominator by 100: \[ \frac{4.8432}{0.08} = \frac{4.8432 \times 100}{0.08 \times 100} = \frac{484.32}{8} \]Step 2: Divide 484.32 by 8 using long division:

    60.54
  _______
8| 484.32
  -48
   ----
    44
   -40
   ----
     43
    -40
    ----
      32
     -32
     ----
       0

Answer:60.54


Q5: Divide each of given numbers by 10, 100, 1000 and 10000:

i. Number: 2.1

Step 1: Divide by 10 (move decimal 1 place left): \[ 2.1 \div 10 = 0.21 \] Step 2: Divide by 100 (move decimal 2 places left): \[ 2.1 \div 100 = 0.021 \] Step 3: Divide by 1000 (move decimal 3 places left): \[ 2.1 \div 1000 = 0.0021 \] Step 4: Divide by 10000 (move decimal 4 places left): \[ 2.1 \div 10000 = 0.00021 \] Answer:0.21, 0.021, 0.0021, 0.00021

ii. Number: 8.64

Step 1: Divide by 10: \[ 8.64 \div 10 = 0.864 \] Step 2: Divide by 100: \[ 8.64 \div 100 = 0.0864 \] Step 3: Divide by 1000: \[ 8.64 \div 1000 = 0.00864 \] Step 4: Divide by 10000: \[ 8.64 \div 10000 = 0.000864 \] Answer:0.864, 0.0864, 0.00864, 0.000864

iii. Number: 5.01

Step 1: Divide by 10: \[ 5.01 \div 10 = 0.501 \] Step 2: Divide by 100: \[ 5.01 \div 100 = 0.0501 \] Step 3: Divide by 1000: \[ 5.01 \div 1000 = 0.00501 \] Step 4: Divide by 10000: \[ 5.01 \div 10000 = 0.000501 \] Answer:0.501, 0.0501, 0.00501, 0.000501

iv. Number: 0.0906

Step 1: Divide by 10: \[ 0.0906 \div 10 = 0.00906 \] Step 2: Divide by 100: \[ 0.0906 \div 100 = 0.000906 \] Step 3: Divide by 1000: \[ 0.0906 \div 1000 = 0.0000906 \] Step 4: Divide by 10000: \[ 0.0906 \div 10000 = 0.00000906 \] Answer:0.00906, 0.000906, 0.0000906, 0.00000906

v. Number: 0.125

Step 1: Divide by 10: \[ 0.125 \div 10 = 0.0125 \] Step 2: Divide by 100: \[ 0.125 \div 100 = 0.00125 \] Step 3: Divide by 1000: \[ 0.125 \div 1000 = 0.000125 \] Step 4: Divide by 10000: \[ 0.125 \div 10000 = 0.0000125 \] Answer:0.0125, 0.00125, 0.000125, 0.0000125

vi. Number: 111.11

Step 1: Divide by 10: \[ 111.11 \div 10 = 11.111 \] Step 2: Divide by 100: \[ 111.11 \div 100 = 1.1111 \] Step 3: Divide by 1000: \[ 111.11 \div 1000 = 0.11111 \] Step 4: Divide by 10000: \[ 111.11 \div 10000 = 0.011111 \] Answer:11.111, 1.1111, 0.11111, 0.011111


Q6: Evaluate:

i. \(9.75 \div 5\)

Step 1: Divide 9.75 by 5 using long division:

    1.95
   _______
5 | 9.75
   -5
   ---
    47
   -45
    ---
     25
    -25
     ---
      0

Answer:1.95

ii. \(4.4064 \div 4\)

Step 1: Divide 4.4064 by 4 using long division:

    1.1016
   _______
4 | 4.4064
   -4
    ---
    04
    -4
     ---
     00
     -0     
     ---
      06
     -04
      ---
       24
      -24
       ---
        0

Answer:1.1016

iii. \(27.69 \div 30\)

Step 1: Multiply numerator and denominator by 10 to remove decimal from divisor: \[ \frac{27.69}{30} = \frac{276.9}{300} \]Step 2: Simplify fraction: divide numerator and denominator by 3: \[ \frac{276.9}{300} = \frac{92.3}{100} \]Step 3: Divide 92.3 by 100 (shift decimal 2 places left): \[ 92.3 \div 100 = 0.923 \]Answer:0.923

iv. \(19.25 \div 25\)

Step 1: Multiply numerator and denominator by 4 to make denominator 100: \[ \frac{19.25}{25} = \frac{19.25 \times 4}{100} = \frac{77}{100} \]Step 2: Divide 77 by 100 (shift decimal 2 places left): \[ 77 \div 100 = 0.77 \]Answer:0.77

v. \(20.64 \div 16\)

Step 1: Divide 20.64 by 16 using long division:

    1.29
   _______
16| 20.64
   -16
    ---
     46
    -32
     ---
     144
    -144
     ----
      0

Answer:1.29

vi. \(3.204 \div 9\)

Step 1: Divide 3.204 by 9 using long division:

    0.356
   _______
9 | 3.204
   -0
   ---
    32
   -27
    ---
     50
    -45
     ---
      54
     -54
      ---
       0

Answer:0.356

vii. \(0.125 \div 25\)

Step 1: Multiply numerator and denominator by 4 to make denominator 100: \[ \frac{0.125}{25} = \frac{0.125 \times 4}{100} = \frac{0.5}{100} \]Step 2: Divide 0.5 by 100 (shift decimal 2 places left): \[ 0.5 \div 100 = 0.005 \]Answer:0.005

viii. \(0.14616 \div 72\)

Step 1: Multiply numerator and denominator by 1000 to remove decimal from numerator: \[ \frac{0.14616}{72} = \frac{146.16}{72000} \]Step 2: Use calculator or simplify fraction to decimal:

     0.00203
    _______
72 | 0.14616
    -0
    ---
     01
    -00
     ---
      14
     -00
     ---
      146
     -144
      ----
        21
       -00
        ----
        216
       -216
        ----
         0

\[ 0.14616 \div 72 = 0.00203 \]Answer:0.00203

ix. \(0.6227 \div 1300\)

Step 1: Multiply numerator and denominator by 10,000 to remove decimal: \[ \frac{0.6227}{1300} = \frac{6227}{13,000,000} \]Step 2: Divide numerator by denominator to get decimal:

           0.000479
          _______
13000000 | 6227
            - 0
           ------
           62270
             - 0
           -------
           622700
              - 0
           ---------
           6227000
               - 0
           ---------
           62270000
          -52000000
          ------------
           102700000
           -91000000
          ------------
            117000000
           -117000000
           -----------
                0

\[ 0.6227 \div 1300 = 0.000479 \]Answer:0.000479

x. \(257.894 \div 0.169\)

Step 1: Multiply numerator and denominator by 1000 to remove decimal from denominator: \[ \frac{257.894}{0.169} = \frac{257894}{169} \]Step 2: Divide 257894 by 169 (long division or calculator):

      1526
     _______
169 | 257894
     -169
      -----
       888
      -845
      ------
        439
       -338
       -------
        1014
       -1014
       ------
          0

\[ 257894 \div 169 = 1526 \]Answer:1526

xi. \(6.3 \div (0.3)^2\)

Step 1: Calculate \((0.3)^2 = 0.09\) \[ 0.3 \times 0.3 = 0.09 \]Step 2: Divide 6.3 by 0.09: \[ 6.3 \div 0.09 \]Step 3: Multiply numerator and denominator by 100 to remove decimal from divisor: \[ \frac{6.3}{0.09} = \frac{630}{9} = 70 \]Answer:70


Q7: Evaluate:

i. \(4.3 \times 0.52 \times 0.3\)

Step 1: Multiply \(4.3 \times 0.52\)

  43
× 52
-----
  86    (43 × 2)
2150   (43 × 50)
-----
2236

Step 2: Place decimal (1 + 2 = 3 decimal places): \[ 4.3 \times 0.52 = 2.236 \]Step 3: Multiply \(2.236 \times 0.3\) \[ 2.236 \times 0.3 = 0.6708 \]Answer:0.6708

ii. \(3.2 \times 2.5 \times 0.7\)

Step 1: Multiply \(3.2 \times 2.5\) \[ 3.2 \times 2.5 = 8.0 \]Step 2: Multiply \(8.0 \times 0.7 = 5.6\)
Answer:5.6

iii. \(0.8 \times 1.5 \times 0.6\)

Step 1: Multiply \(0.8 \times 1.5 = 1.2\)
Step 2: Multiply \(1.2 \times 0.6 = 0.72\)
Answer:0.72

iv. \(0.3 \times 0.3 \times 0.3\)

Step 1: Multiply \(0.3 \times 0.3 = 0.09\)
Step 2: Multiply \(0.09 \times 0.3 = 0.027\)
Answer:0.027

v. \(1.2 \times 1.2 \times 4\)

Step 1: Multiply \(1.2 \times 1.2 = 1.44\)
Step 2: Multiply \(1.44 \times 4 = 5.76\)
Answer:5.76

vi. \(0.4 \times 0.04 \times 0.004\)

Step 1: Multiply \(0.4 \times 0.04 = 0.016\)
Step 2: Multiply \(0.016 \times 0.004 = 0.000064\)
Answer:0.000064

vii. \(0.5 \times 0.6 \times 0.7\)

Step 1: Multiply \(0.5 \times 0.6 = 0.3\)
Step 2: Multiply \(0.3 \times 0.7 = 0.21\)
Answer:0.21

viii. \(0.5 \times 0.06 \times 0.007\)

Step 1: Multiply \(0.5 \times 0.06 = 0.03\)
Step 2: Multiply \(0.03 \times 0.007 = 0.00021\)
Answer:0.00021


Q8: Evaluate:

i. \(\left(0.9\right)^2\)

Step 1: Multiply \(0.9 \times 0.9\)

  9
× 9
---
 81

Step 2: Place decimal back (1 + 1 = 2 decimal places): \[ (0.9)^2 = 0.81 \]Answer:0.81

ii. \(\left(0.6\right)^2 \times 0.5\)

Step 1: Calculate \((0.6)^2 = 0.6 \times 0.6 = 0.36\)
Step 2: Multiply \(0.36 \times 0.5\) \[ 0.36 \times 0.5 = 0.18 \]Answer:0.18

iii. \(0.3 \times \left(0.5\right)^2\)

Step 1: Calculate \((0.5)^2 = 0.5 \times 0.5 = 0.25\)
Step 2: Multiply \(0.3 \times 0.25 = 0.075\)
Answer:0.075

iv. \(\left(0.4\right)^3\)

Step 1: Multiply \(0.4 \times 0.4 = 0.16\)
Step 2: Multiply \(0.16 \times 0.4 = 0.064\)
Answer:0.064

v. \(\left(0.2\right)^3 \times 5\)

Step 1: Calculate \((0.2)^3\) \[ 0.2 \times 0.2 = 0.04, \quad 0.04 \times 0.2 = 0.008 \]Step 2: Multiply \(0.008 \times 5 = 0.04\)
Answer:0.04

vi. \(\left(0.2\right)^3 \times 0.05\)

Step 1: Calculate \((0.2)^3 = 0.008\) (from above)
Step 2: Multiply \(0.008 \times 0.05\) \[ 0.008 \times 0.05 = 0.0004 \]Answer:0.0004


Q9: Find the cost of 36.75 kg wheat at rate of ₹12.80 per kg.

Step 1: Write the multiplication expression: \[ \text{Cost} = 36.75 \times 12.80 \]Step 2: Remove decimals and multiply \(3675 \times 1280\):

   3675
 × 1280
──────────
   0000    (3675 × 0)
 294000    (3675 × 80)
 735000    (3675 × 200)
3675000    (3675 × 1000)
──────────
4704000

Step 3: Place decimal back: Total decimal places = 2 (in 36.75) + 2 (in 12.80) = 4 \[ 36.75 \times 12.80 = 470.4000 = 470.4 \]Answer:₹470.40


Q10: The cost of a pen is ₹56.15. Find the cost of 16 such pens.

Step 1: Write the multiplication expression: \[ \text{Total cost} = 56.15 \times 16 \]Step 2: Remove decimal and multiply \(5615 \times 16\):

 5615
 × 16
───────
 33690   (5615 × 6)
 56150  (5615 × 10)
───────
 89840

Step 3: Place decimal back:
Decimal places in 56.15 = 2 \[ 56.15 \times 16 = 898.40 \]Answer:₹898.40


Q11: Evaluate

i. \(0.0072 \div 0.06\)

Step 1: Remove decimals by multiplying numerator and denominator by 1000: \[ \frac{0.0072}{0.06} = \frac{7.2}{60} \] Step 2: Divide \(7.2 \div 60\):

      0.12
    _______
60 | 7.2
    -0
    ----
     72
    -60
     ----
     120
    -120
     ---
      0

Answer:0.12

ii. \(0.621 \div 0.3\)

Step 1: Remove decimals by multiplying numerator and denominator by 10: \[ \frac{0.621}{0.3} = \frac{6.21}{3} \] Step 2: Divide \(6.21 \div 3\):

    2.07
   _______
3 | 6.21
   -6
    ----
     02
    -00
     ----
      21
     -21
      ---
       0

Answer:2.07

iii. \(0.0532 \div 0.005\)

Step 1: Remove decimals by multiplying numerator and denominator by 1000: \[ \frac{0.0532}{0.005} = \frac{53.2}{5} \] Step 2: Divide \(53.2 \div 5\):

    10.64
   _______
5 | 53.2
   -5
    ----
     3
    -0
     ----
      32
     -30
      ---
       20
      -20
       ---
        0

Answer:10.64

iv. \(0.01162 \div 0.14\)

Step 1: Remove decimals by multiplying numerator and denominator by 100: \[ \frac{0.01162}{0.14} = \frac{1.162}{14} \] Step 2: Divide \(1.162 \div 14\):

     0.083
    _______
14 | 1.162
    -0
     ----
     11
     -0
     ---
     116
    -112
     ----
       42
      -42
       ---
        0

Answer:0.083

v. \(\left(7.5 \times 40.4\right) \div 25\)

Step 1: Multiply \(7.5 \times 40.4\):

   404
 ×  75
───────
  2020   (404 × 5)
 28280   (404 × 70)
───────
 30300

Since \(7.5 \times 40.4 = 303.0\) (decimal places 1 + 1 = 2, so 3030 ÷ 100 = 303.0)
Step 2: Divide \(303.0 \div 25\):

    12.12
    _______
25 | 303.0
    -25
    ----
      53
     -50
     ----
       30
      -25
      ---
        50
       -50
        ---
         0

Answer:12.12

vi. \(2.1 \div (0.1 \times 0.1)\)

Step 1: Multiply \(0.1 \times 0.1 = 0.01\)
Step 2: Divide \(2.1 \div 0.01\):

2.1 ÷ 0.01 = 210

Answer:210


Q12: Fifteen identical articles weigh 31.50 kg. Find the weigh of each article.

Step 1: Total weight of 15 articles = 31.50 kg
Let weight of each article = \(x\) kg.
So, \(15 \times x = 31.50\)

Step 2: Find \(x\) by dividing total weight by number of articles: \[ x = \frac{31.50}{15} \]

     2.1
    _______
15 | 31.50
    -30
     ---
      15
     -15
      ---
      0

Answer: Each article weighs 2.1 kg.


Q13: The product of two numbers is 211.2. If one of these two numbers is 16.5, find the other number.

Step 1: Let the other number be \(x\).
Given, \[ 16.5 \times x = 211.2 \]Step 2: Find \(x\) by dividing 211.2 by 16.5: \[ x = \frac{211.2}{16.5} \]

      12.8 
     _______
165 | 2112
     -165
      ----
       462
      -330
       ----
       1320
      -1320
      ------
        0

Answer: The other number is 12.8.


Q14: One dozen identical articles cost ₹45.96. Find the cost of each article.

Step 1: One dozen means 12 articles. Let the cost of each article be \(x\).
Given, \[ 12 \times x = 45.96 \]Step 2: Find \(x\) by dividing 45.96 by 12: \[ x = \frac{45.96}{12} \]

      3.83
    _______
12 | 45.96
    -36
    ----
      99
     -96
     ----
       36
      -36
       ---
       0

Answer: The cost of each article is ₹3.83.


Q15: Find whether the given division forms a terminating or a non-terminating decimal:

i. \(3\div8\)

Step 1: Prime factorize the denominator 8 = \(2^3\).
Since denominator has only 2 as prime factors, division gives a terminating decimal.
Answer: Terminating decimal.

ii. \(8 \div 3\)

Step 1: Denominator 3 is prime.
Division gives a repeating decimal (non-terminating).
Answer: Non-terminating decimal.

iii. \(6 \div 5\)

Step 1: Denominator 5 is prime.
Division gives a terminating decimal.
Answer: Terminating decimal.

iv. \(5 \div 6\)

Step 1: Denominator 6 = \(2 \times 3\) includes 3, so non-terminating decimal.
Answer: Non-terminating decimal.

v. \(12.5 \div 4\)

Step 1: Denominator 4 = \(2^2\), only 2’s prime factors.
Division gives terminating decimal.
Answer: Terminating decimal.

vi. \(23 \div 0.7 = \frac{23}{0.7} = \frac{230}{7}\)

Step 1: Denominator 7 is prime (other than 2 or 5), so division is non-terminating decimal.
Answer: Non-terminating decimal.

vii. \(42 \div 9\)

Step 1: Denominator 9 = \(3^2\), prime factor is 3, non-terminating decimal.
Answer: Non-terminating decimal.

viii. \(0.56 \div 0.11 = \frac{56}{11}\)

Step 1: Denominator 11 is prime, division is non-terminating decimal.
Answer: Non-terminating decimal.


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