1, 3, 7, 21.
The factors of 21 are: 1, 3, 7, 21. The factors of 56 are: 1, 2, 4, 7, 8, 14, 28, 56.
The positive integer factors of 273 are:1, 3, 7, 13, 21, 39, 91, 2731,3 7,13,21,39,91,273
When the "factors" of a number are listed, the list is usually restricted to positive factors. Then there would be no answer to the question, because no group of positive numbers can add up to make zero.
Other than the number 1, there are no positive integer common factors of 10 and 21.
It is an odd number. It is not prime. Its factors are 1, 3, 7 and 21. It is positive.
The positive integer factors of 987 are: 1, 3, 7, 21, 47, 141, 329, 987
The factor pairs of 21 are:1, 213, 7Therefore, the number 21 has two pairs of positive integer factors.
The factors of 13 are: 1, 13 The factors of 21 are: 1, 3, 7, 21 The factors of 63 are: 1, 3, 7, 9, 21, 63 because these are the positive integers that divide evenly into 63 with no remainder. The factors of 79 are: 1, 79
The factors of 84 are: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
The factors of 21 are: 1, 3, 7, 21.The factors of 84 are: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84.The common factors are: 1, 3, 7, 21
Since the numbers 20 and 21 share no common positive integer factors, 20/21 is expressed in its simplest form.