A prime number is a number that does not have any multiples beside itself, whereas composite numbers have other multiples that make up the number. In this case,

3 x 17 = 51, which is why it is composite.
A Composite Number
composite number is defined as numbers with factors other than 1 and itself..

since 3*17=51..

51 is a composite #.. 😉
17 * 3 = 51
Erica said that 51 is a composite number. Jimmy said 51 is a prime number. Who is right? How do you know?
Yes, it’s not prime because 17 x 3 = 51.
It can be divided by 17 , 3 times!! 🙂
Because you touch yourself at night.

why is 51 a composite number?