I need help solving a problem, I am stuck on this one.

Question

Write 128 in each one of the following bases a.Five
b. Two
c. Twelve

Answer 1

a) 128 = (5 * 25) + (3 * 1) = (5 * 5^2) + (0 * 5^1) + (3 * 5^0)
in base 5 __ 503

b)128 = 2^7 = (1 * 2^7) + (0 * 2^6) + (0 * 2^5) + (0 * 2^4) + (0 * 2^3) + (0 * 2^2) + (0 * 2^1) + (0 * 2^0)
in base 2 __ 10000000

c) 128 = (10 * 12) + (8 * 1) = (10 * 12^1) + (8 * 12^0)
in base 12 __ A8

9 is our largest numerical digit, so we switch to letters after that

Answer 2

Scott's answer is correct except for A. 128 in base 5 should be written as 1003 because you cannot use the number 5 in your answer.