Basic idea: every two into one

For example, 1+1=10; 1+10=11; 10+10=100; 1+11=100; 10+11=101;

For example, 1 (2) = 1 (10)

10 (binary) = 2 (decimal)

11 (binary) = 3 (decimal)

100 (binary) = 4 (decimal)