Is 25 a multiple of 2 or 5? How do you know?

Simply list out the multiples of #2# and #5# first. See below:

Multiples of #5# include: #5#, #10#, #15#, #20#, #25#, #30#, #35#, and etc.

Multiples of #2# Include: #2#, #4#, #6#, #8#, #10#, #12#, #14#, #16#, #18#, #20#, #22#, #24#, #26# and etc.

As we can see, the multiples of #2# skip the number #25# so we can immediately assume that #25# is not a multiple of #2#. Therefore it must be a multiple of #5#.

And this makes sense right?

#5+5+5+5+5=25#.

#5^2=25#.

#5*5=25#.

Whatever way you want to think about it works.

Answer: #5#
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Foot note:

Any multiple of 2 is even. However 25 is odd so it can not be a multiple of 2.

1. If the last digit is 0 or 5 then the number is divisible by 5.
2. if the last digit is 0,2,4,6,8 then the number is divisible by 2.

From 1 and 2 :

25 has last digit 5

=> 25 is divisible by 5

Multiples of 5 always end with a #5# or a #0# and multiples of 2 always end with a even number or #0#.

Since #25# ends with #5#, it 25 is a multiple of 5!

My source is my mind.

I hope that helps you!

-Moksha