Page 143 - New Medley 5 Semester 1

To multiply a number by 50, put two zeros to the right of the number
and divide it by 2.

Examples: 436 × 50 = 43600 ÷ 2 = 21800, 7394 × 50
= 739400 ÷ 2 = 369700, etc.

Z Z Multiplication by numbers like 9, 99, 999, etc., and 11, 101, 1001, etc.

Consider the following addition-subtraction facts:

10 – 1 = 9 and 10 + 1 = 11

100 – 1 = 99 and 100 + 1 = 101

1000 – 1 = 999 and 1000 + 1 = 1001 and so on.

These facts make a multiplication simpler. To clarify the concept, observe
the following examples:

596 × 9 = 596 × (10 – 1) = 5960 – 596 = 5364

and 596 × 11 = 596 × (10 + 1) = 5960 + 596 = 6556

384 × 99 = 384 × (100 – 1) = 38400 – 384 = 38016

and 384 × 101 = 384 × (100 + 1) = 38400 + 384 = 38784

5273 × 999 = 5273 × (1000 – 1)

= 5273000 – 5273 = 5267727

and 5273 × 1001 = 5273 × (1000 + 1)

= 5273000 + 5273 = 5278273

Z Z Multiplication of a number ending with 5 by itself. (Vedic Maths Trick)

Consider the multiplication 25 × 25.

In the number 25, the ones digit is 2. Multiply 2 by its successor, i.e.,
2 × 3 = 6. Now, put 25 to the right of product, i.e., 625 which is the

product of 25 × 25. Other examples are:

15 × 15 = 225 ( 1 × 2 = 2)

65 × 65 = 4225 ( 6 × 7 = 42)

125 × 125 = 15625 ( 12 × 13 = 156)

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