A factor is a number that divides into another number without having a remainder. For the number 42, you can ask yourself what integers can be multiplied together to give a product of 42.
1 and 42 can be multiplied to give a product of 42.
2 and 21.
3 and 14.
And finally, 6 and 7 can also be multiplied to give a product of 42.
These are the factors of 42.
From the list provided, 7 and 21 are factors of 42.