whats the remainder when 2^k is divided by 10. 1. k is

Question

whats the remainder when 2^k is divided by 10. 
1. k is divisible by 10 
2. k is divisible by 4

crackgmat3 · Answer

B.

1) Insufficient - when k is divisible by 10, it can be 10,20,..
2^10 and 2^20 have different unit digits

2) sufficient - when k is divisible by 4, it can be 4,8,12, ... 
2^4 or 2^8 have the same unit digit.

intr3pid · Answer

B is true only if k is positive.

If k is negative, the numbers are: 2^(-4), 2^(-8), and so on.

This corresponds to: 1/16, 1/256, 1/4096.

Divide them by 10 (i.e., 10 times 0 is 0 and then the remainder), and your remainders are 1/16, 1/256, 1/4056, which are all different.

hardworker_indian · Answer

For the above series, where k is negative, I guess the reminders should be all ones!

cbrf3 · Answer

ALL, can we consider the case when 'k" = 0...........I would say 0 is divisible by 4 but 2^0 = 1 and hence when divided by 4 would yield remainder 1.........wotsay everyone??

whats the remainder when 2^k is divided by 10. 1. k is

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