Answer: 2×2×5×7 or, in exponent form,
×
×

Explanation:
We can use a factor tree to determine the prime factorization of 140. You may notice that there are several factors to choose from that will give us 140, but you can choose any because in the end it will give you the same answer!
140
14 × 10
2×7 2×5
That is all, because the final numbers listed are prime and we cannot perform any further actions.
Hope this helps!