Express the following numbers as a product of its prime factors:140.

Hint:
We will first divide 140 by the smallest prime that divides it completely, that is 2. Then, write the quotient, which comes out to be 70 in the next column under 140 and again find the smallest prime number which divides 70 and then repeat the same process until the quotient becomes 1. At last, express the number as the product of primes obtained in prime-factorisation of the number.

Complete step by step solution:
We have to write the number 140 as the product of its prime factors.
That is, we have to write the prime-factorisation of the number, 140
Prime numbers are the numbers that have only 2 factors.
We will divide the number 140 by the smallest prime number which divides it, that is 2.
Then, write the quotient, which comes out to be 70 in the next column under 140 and again find the smallest prime number which divides 70 and then repeat the same process until the quotient becomes 1.

Now, we can write 140 as $2 \times 2 \times 5 \times 7$, which is the product of the prime numbers.

Note:
If we multiply the numbers of prime factorisation of the number, we will get back the same number. 2 is the smallest even prime number and all even numbers are divisible by 2. The prime-factorisation of a number also helps to determine the factors of the number.