Question: What is the result of converting the binary number 10101 to decimal?

Options:

1. 21
2. 20
3. 19
4. 22

Correct Answer: 21

Solution:

10101 in binary equals 1*2^4 + 0*2^3 + 1*2^2 + 0*2^1 + 1*2^0 = 21.