Complex divisions (II)


Children need practice in dividing by 10, 100, and 1000 also, to handle complex divisions. For teaching division by 10, remind children of their exercises in place-value. They read 326 as 3 hundred 2 tens 6 units or, if one likes, 32 tens and 6 units. So, 326 ÷ 10 (how many 10's in 326?) gives the answer 32 and 6 over.

Whichever method is used, on inspecting the answer a quick way of dividing by 10 can be seen − separate off the unit digit as remainder, and the other digits in the right order give the quotient:

  • 762 ÷ 10 = 76 and 2 over
  • 1351 ÷ 10 = 135 and 1 over
  • 79 ÷ 10 = 7 and 9 over
  • 6 ÷ 10 = 0 and 6 over

On the basis of this observation children can easily find quick way to divide by 100. Confirm this by giving following types of examples, to try.

  • 231 ÷ 100 = 2 and 31 over
  • 1351 ÷ 100 = 13 and 51 over
  • 79 ÷ 100 = 0 and 79 over
  • 4 ÷ 100 = 0 and 4 over

Allow children time to inspect the answers obtained. They suggest the quick way to divide by 100 − separate off the ten and unit digit in the right order, as remainder. Obviously, the other digits in the right order give the quotient.

Lead children to quick method of dividing by 1000, as shown above.

When children can divide by 1-9, by 10 and the multiples of 10, they are ready for two-digit divisors. At this stage it is necessary to provide carefully graded practice in division. Use the following numbers first: 11, 12, 21, 22, 31, 32, 41, 42, 19, 29, and 39, as divisors. Then go on to the divisors 24, 36, 47, etc. This rearrangement of the divisors presents less difficulty to the children when they are finding an approximate quotient.

The dividend at first should not be more than three digits, and give many one-step examples to make children gradually familiar with the appearance of the long-division setting.

To help backward children keep the divisor same throughout in each example of the early lessons.

e.g.

  • 87 ÷ 21
  • 179 ÷ 21
  • 205 ÷ 31

In long division it is necessary to put the figures in the quotient in their right column. Therefore, in the initial practice children should be asked to put zero in the quotient (although it is meaningless in forming a number).

The copyright of the article Complex divisions (II) in Math for Kids is owned by Vidya Narayan Wadadekar . Permission to republish Complex divisions (II) in print or online must be granted by the author in writing.

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