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Thursday, 16 December 2010

How to do Long division tricks for kids

"In arithmetic, long division is a standard procedure suitable for dividing simple or complex multidigit numbers. It breaks down a division problem into a series of easier steps. As in all division problems, one number, called the dividend, is divided by another, called the divisor, producing a result called the quotient. It enables computations involving arbitrarily large numbers to be performed by following a series of simple steps"


Solution for 742 ÷ 31 - with remainder

Step 1

Long division works from left to right. Since 31 will not go into 7, a grey 0 has been placed over the 7 and we combine the first two digits to make 74. Note the other digits in the original number have been turned grey to emphasise this.
The closest we can get to 74 without exceeding it is 62 which is 2 × 31. These values have been added to the division, highlighted in red.

02
 rem 29

31742

62

31 × table
1 × 31 =31
2 × 31 =62
3 × 31 =93
4 × 31 =124
5 × 31 =155
6 × 31 =186
7 × 31 =217
8 × 31 =248
9 × 31 =279

Step 2

Next, work out the remainder by subtracting 62 from 74. This gives us 12. Bring down the 2 to make a new target of 122.

2
 rem 29

31742

62

122

31 × table
1 × 31 =31
2 × 31 =62
3 × 31 =93
4 × 31 =124
5 × 31 =155
6 × 31 =186
7 × 31 =217
8 × 31 =248
9 × 31 =279

Step 3

With a target of 122, the closest we can get is 93 by multiplying 31 by 3. Write the 93 below the 122 as shown.

23 rem 29

31742

62

122

93

31 × table
1 × 31 =31
2 × 31 =62
3 × 31 =93
4 × 31 =124
5 × 31 =155
6 × 31 =186
7 × 31 =217
8 × 31 =248
9 × 31 =279

Step 4

Finally, subtract 93 from 122 giving 29. Since there are no other digits to bring down, 29 is therefore also the remainder for the whole sum.
So 742 ÷ 31 = 23 rem 29

23 rem 29

31742

62

122

93

29

31 × table
1 × 31 =31
2 × 31 =62
3 × 31 =93
4 × 31 =124
5 × 31 =155
6 × 31 =186
7 × 31 =217
8 × 31 =248
9 × 31 =279

Long division traditional method

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