Binary numeral system
Base-2 number system (binary numeral system), represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2. Because of its straightforward implementation, the binary system is used internally by almost all modern computers.
For example:
The decimal number 13 can be represented like 1101 in binary.
20 = 1, 21= 2, 22 = 4, 23 = 8 ......
23 22 21 20
1 1 0 1
8 4 0 1 = (8+4+0+1 = 13)
1101:
13= 1 x 23 + 1 x 22 + 0 x 21 + 1 x 20
Sources:
https://en.wikipedia.org/wiki/Binary_numeral_system
https://www.bookrags.com/research/binary-number-system-wom/