How do you find all the factors of the number 45?

1 Answer
Dec 19, 2016

the factors of " "45:{1,3,5,9,15,45}

Explanation:

The best way would be to systematically find pairs of number that multiply to give 45

so" "color(red)1xxcolor(red)(45)=45

45" "ends in a 5 so ""5"" must be a factor

" "color(red)5xxcolor(red)(9)=45

we can now use factors of the factors where possible

9=3xx3" " we can use 3

" "color(red)3xxcolor(red)(15)=45

15has " "3" "&" "5" "which we have already used

any other combination gives a number greater than half of " "45" " so we have found them all

so all the factors of " "45:{1,3,5,9,15,45}