Guest

Multiplying by 9 is really multiplying by 10-1. So, 9x9 is just 9x(10-1) which is 9x10-9 which is 90-9 or 81. Lets try a harder example: 46x9 = 46x10-46 = 460-46 = 414. One more example: 68x9 = 680-68 = 612. To multiply by 99, you multiply by 100-1. So, 46x99 = 46x(100-1) = 4600-46 = 4554. Multiplying by 999 is similar to multiplying by 9 and by 99. 38x999 = 38x(1000-1) = 38000-38 = 37962.


Multiplying by 9 is really multiplying by 10-1.


So, 9x9 is just 9x(10-1) which is 9x10-9 which is 90-9 or 81.




Lets try a harder example: 46x9 = 46x10-46 = 460-46 = 414.




One more example: 68x9 = 680-68 = 612.




To multiply by 99, you multiply by 100-1.


So, 46x99 = 46x(100-1) = 4600-46 = 4554.




Multiplying by 999 is similar to multiplying by 9 and by 99.


38x999 = 38x(1000-1) = 38000-38 = 37962.


Grade:11

1 Answers

Nishant Vora IIT Patna
askIITians Faculty 2467 Points
8 years ago
Dear student,
yes thats a very powerful techniq

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free