3
3 is a prime factor of 12 and of 21.
'3' 3 x 4 = 12 3 x 7 = 21 NB '7' is also a prime number.
No. The only factors of a prime number are 1 and itself. The only way that 21 could be a factor of a prime number is if it were a prime number, but it is not because 21 is also divisible by 3 and 7.
3
If 21 is a multiple of the number, the number cannot have 90 as a factor.
21 is not a prime factor, it is 3 x 7
3 and 7
21 = 3 x 7 both 3 and 7 are prime numbers
7
3 and 7
They are: 3 and 7
prime factor = prime number which can be divided into the given number with no remainder The prime factors of 21 are 3 and 7.