The prime factor of the number 28 is 2(2) and 7.

2X2X7 are prime numbers.

The prime factor of the number 40 is 2(3) and 5.

2 x 2 x 2 x 5 are prime numbers

The prime factor of the number 42 is 2 and 3 and 7.

2 x 3 x 7 are prime numbers.

2X2X7 are prime numbers.

The prime factor of the number 40 is 2(3) and 5.

2 x 2 x 2 x 5 are prime numbers

The prime factor of the number 42 is 2 and 3 and 7.

2 x 3 x 7 are prime numbers.