50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100
All of them except for 83, 89 and 97 which are prime numbers
The GCF of all the composite numbers under 100 is 1. For e.g 4 & 9 are composite numbers & their GCF is 1, so if we take other composite numbers along with 4 & 9 the GCF will be 1.
The sum of these composite numbers, including 100, is 3989.The sum of all numbers between 1 and 100 is 5,050. From this we need to subtract the sum of 1 plus all the prime numbers below 100. The sum of the primes is 1,060. Subtracting (1 + 1060) or 1,061 from 5,050 yields 3,989.
All even numbers between 50 and 80 are composite.
101