Binary form of 18 is "10010"
18 in binary is 10010
Decimal 23 is 10111 in binary
Decimal 26 is 11010 in binary
Decimal 27 is 11011 in binary
11001 16 + 8 + 1
Decimal 28 is 11100 in binary
Decimal 20 is 10100 in binary
10010
10010
10010=18 the places held for each 1 and 0 in binary are 16,8,4,2,1 so 10010 is 16+2 = 18
212 (decimal) is 11010100 (binary)