Discussion of Question with ID = 042 under Basic-Simplification

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Question

What is 139 × 25?

A

3475.

B

3480.

C

3470.

D

3485.

Soln.
Ans: a

This is a multiplication by a power of 5. The best way is to observe that 25 = 52. There are 2 powers of 5. So append 2 zeroes and divide by 22, like this: $13900/4$ = 3475.


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