The product with a factor of 10 end in

The factors of 10 are 1, 2, 5, and 10. You can also look at this the other way around: if you can multiply two whole numbers to create a third number, those two numbers are factors of the third. 2 x 5 = 10, so 2 and 5 are factors of 10. 1 x 10 = 10, so 1 and 10 are also factors of 10.