Analysis (30 seconds): The question is asking me to find the 10th digit of \(0.2^1^0\), the answer choices look familiar, possibly the pattern of final digits for powers of 2. I have absolutely no idea how to calculate the actual value of this so I'm going to go ahead and assume two things : 1) I can ignore the fact that the number is a decimal and focus on the 2, and 2) the 10th digit is actually the last digit (because I'm confident GMAC don't actually want me to compute the value of \(0.2^1^0\)). In order to solve this I'll quickly refresh my memory on the pattern of end digits for powers of 2 and then see what the 10th power would yield.
Strategy: Find the pattern, Count to 10
Find the pattern (30 seconds):
\(2^0 = 0\)
\(2^1 = 2\)
\(2^2 = 4\)
\(2^3 = 8\)
\(2^4 = 16\)
\(2^5 = 32\)
Looks like the pattern is: [2,4,8,6] with the exception of 0.
Count to 10 (10 seconds):
Using [2,4,8,6] as the pattern and starting from index 1 I can see that the 10th power will give me an end digit of 4.
Answer = C
Total Time: 1:10