NCERT Solutions
Class 6 Maths
Playing with Numbers

Ex. 3.5 Q.8
In which of the following expressions, prime factorization has been done:
(a) 24 = 2 * 3 * 4 (b) 56 = 7 * 2 * 2 * 2 (c) 70 = 2 * 5 * 7 (d) 54 = 2 * 3 * 9
(a) Given, 24 = 2 * 3 * 4
Since 4 can be factorize as 2 * 2
So, it is not a prime factorization.
(b) Given, 56 = 7 * 2 * 2 * 2
Since all numbers are prime,
So, it is a prime factorization.
(c) Given, 70 = 2 * 5 * 7
Since all numbers are prime,
So, it is a prime factorization.
(d) Given, 54 = 2 * 3 * 9
Since 9 can be factorize as 3 * 3
So, it is not a prime factorization.
Hence, in expressions (b) and (c), prime factorization has been done.