Doubts

1) I found it best to pick numbers for this problem.

n = 1

(7^(4n+3))(6^n) = (7^7)*6

you can figure out the pattern of the powers of 7 by multiplying its units digits.

7 49...

9*7 = 63 (units digit will be 3)
3*7 = 21 (units digit will be 1)
1*7 = 7 (units digit will be 7)

so the pattern goes: 7 9 3 1...repeat the set again. 7^7 power will have a units digit of 3.

units digit of 6^1 is 6

multiply both units digits; we get 6*3 = 18 (8 is the units digit)

for a number to be divisible by 10, it should end in 0. the product of (7^7)(6^1) is 8 digits away from the last zero number.

so remainder is 8.

2) I don't know why but I get D as my answer.

for the side to be round off to it's nearest centimeter, IMO it is 5.5 since it is the smallest number where it can be rounded off to 6.0

5.5^2 = (11/2)(11/2) = 121/4 = 30.25

Yeah I get D for (2) too. Not sure why it is C. Anybody??

yogami wrote:Yeah I get D for (2) too. Not sure why it is C. Anybody??

Second question, D for me too 5.5*5.5=30.25
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