The binary equivalent of 25 is:

111001 11001 10001 10011

11001

$25 = 16 + 8 + 1 = 1 × 2^4 + 1 × 2^3 + 0 × 2^2 + 0 × 2^1 + 1 × 2^0$ ∴ Binary equivalent = 11001