What are the rightmost four digits of the binary equivalent of the decimal number 4739685
My approach–
I converted the whole number into its binary equivalent and then checked out the last 4 digits, is there any shorter way to find it directly, I was thinking as in the case of finding last 4 digits in base 10 we do mod 10^4, so is there anything like 2^4 that we can do to find the last 4 digits in this case ? like 4739685 mod 16 ?
Best Answer
Last 4 digits of binary = Last hex-digit of hexadecimal
$10^4 \pmod{16} ≡ 2^4×5^4 \pmod{2^4} ≡ 0$
$4739685 \pmod{16} ≡ 9685-10000 \pmod{16} ≡ -315+320 \pmod{16} ≡ 5$
hex-digit of 5 = binary of 0101