Answer
84
Work Step by Step
We start counting from 0 from the most right digit.
1010100 (Binary number)
6543210 (Position/Index which represents the exponent)
1010100 = $1 \times 2^{6} + 0\times 2^{5} + 1 \times 2^{4} + 0\times 2^{3} + 1 \times 2^{2}+ 0\times 2^{1} + 0\times 2^{0} $
= 64 + 16+4
= 84
