To multiply a number,

*a*, by a number,

*b*, that is near to 100, here are the steps.

- Multiply the multiplicand by 100.

c = 100 x*b* - Subtract 100 from the multiplier.
*d*=*b*- 100 - Multiply multiplicand,
*a*with the result from step 3,*d*.*e*= d x a - Finally, add the result from steps 1 and 3.

In simple words, we could write it as

( 100 x multiplicand ) + ( (multiplier - 100) x multiplicand )

### Example:

- 101 x 23 = (100 x 23) + ( (101 - 100) x 23 ) = 2300 + (1 x 23) = 2300 + 23 = 2323
- 99 x 23 = (100 x 23) + ( (99 - 100) x 23 ) = 2300 + (-1 x 23) = 2300 - 23 = 2277

Now, you can try to do it on larger numbers such as 101 x 297, or even slightly larger or smaller than 100 multiplier, such as 103 x 74.

my brain so slow..long time just use calculator..hehe

ReplyDeleteGOOD TUTOR!

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