Yup, right on the money.
Each digit in a binary number equals either 0 or 1, times 2 raised to a power. The rightmost digit always starts at 2 raised to the 0 power (2^0) which is decimal value 1. Then the next digit is 2^1 (decimal value 2), then the next is 2^2 (decimal value 4), etc.
So 101010 = (1 * 2^5) + (0 * 2^4) + (1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (0 * 2^0) = 32 + 0 + 8 + 0 + 2 + 0 = 42
Also, decimal value for ASCII "4" is 0011 0100, and for ASCII "2" is 0011 0010, like you said.
The actual ASCII character for decimal value 42 is the wildcard character *.