Friday, 19 October, 2007

Fascinating technique

If you want to multiply any number with 9, 99, 999, so on

Consider the following examples
Example 1
99 X 42 = 4158

Procedure
Step 1 Subtract 1 from 42, we get 41
Step 2 Now, Subtract 41 from 99, we get 58

Answer is 4158

Example 2
999x343=342657

Procedure
Step 1 343 – 1 = 342
Step 2 9-3 = 6, 9-4 = 5, 9-2 = 7

Answer is 342657

1 comment:

Jane said...

Ramneek,
Hi, I have been collecting little fascinations like this too. Do you find these little exercises grab the student's attention? Is this the case for Secondary students?
I did a podcast (a bit lame) about this on my About Page:
http://jamorgan.edublogs.org/about/

 

Apture