Question

Question #490ed

Answer 1

Prime numbers have exactly `2` factors.

Explanation:

Count the number of factors that a number has.

A PRIME number has exactly TWO factors - 1 and itself.

The first prime numbers are:

`2" "3" "5" "7" "11" "13" "17" "19" "23" "29" "31" "37.....`

1 is not a prime number becasue it only has ONE factor - `1`

Numbers which have THREE or more factors are COMPOSITE.

Here is a list of the factors of the numbers up to 12.

`1: rarr 1`
`2:rarr color(red)(1," "2)`
`3:rarr color(red)(1," "3)`
`4:rarr 1," "2," "4`
`5:rarr color(red)(1," "5)`
`6:rarr 1," "2," "3," "6`
`7:rarr color(red)(1," "7)`
`8:rarr 1," "2," "4," "8`
`9:rarr 1," "3," "9`
`10:rarr 1," "2," "5," "10`
`11:rarr color(red)(1," "11)`
`12:rarr 1," "2," "3," "4," "6," "12`

The prime numbers are shown in red:
They all have exactly `2` factors.