Factors are the numbers by which a big number is divided into small numbers.
e.g. let's talk about 10
10=2×5, now if we take 20.
20=2×10
Here, 10 can be written as 2×5, i.e.
20=2×2×5
=4×5
Thus, we can say that 10 has two factors 2&5.
Whereas, 20 has two factors 2&10
Again, 4&5 are also its factors.