Question #490ed

1 Answer
EZ as pi
Apr 12, 2017

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.

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