Quick Multiplication Technique For Special Numbers

Quick Multiplication Technique for Some Special Numbers

Eg: (a) 82 88, (b) 65 65, (c) 44 46

This Multiplication trick works when sum of digits at units place add up to 10 and other digits should be same.

(a) ((a) 82 88

Increase one of the tens digits by one and multiply by other digit. In this case it is, 9 8 = 72

Multiply Units digits, and write down. In this case it is, 2 8 = 16.

8

2

8

8

72 (9 8)

16 (2 8)

So, 82 88 = 7,216
T(b(b) 65 65

Increase one of the tens digits by one and multiply by other digit. In this case it is, 7 6 = 42

Multiply Units digits, and write down. In this case it is, 5 5 = 25

6

5

6

5

42 (7 6)

25 (5 5)

So, 65 65 = 4,225

T(c (c) 44 46

Increase one of the tens digits by one and multiply by other digit. In this case it is, 5 4 = 20

Multiply Units digits, and write down. In this case it is, 4 6 = 24

4

4

4

6

20 (5 4)

24 (4 6)

So, 44 46 = 2,024

This technique is especially useful to find squares of numbers ending that end in 5.

For example we can quickly do 145 145.

Multiply Units digits, and write down. In this case it is, 5 5 = 25

For remaining numbers, increase one of them by 1 and multiply by other number. In this case it is, 15 14 = 210

14

5

14

5

210 (15 14)

So, 145 145 = 21,025

This resource was uploaded by: Akash