# Divisibility problem

• Jun 24th 2012, 09:57 PM
MikeNoob
Divisibility problem
Quote:

IF m is divisible by 5 what is the largest number that must be evenly divisible into 5m + 25 ? Ans=25
How did they get 25 here?
• Jun 24th 2012, 10:33 PM
biffboy
Re: Divisibility problem
Quote:

Originally Posted by MikeNoob
How did they get 25 here?

If m is divisible by 5 then we can write m=5k So 5m+25=25k+25=25(k+1)
• Jun 24th 2012, 11:56 PM
Deveno
Re: Divisibility problem
honestly, it seems the correct answer is 5m + 25, which surely divides 5m + 25 (and may be bigger than 25, if m is larger than 5).
• Jun 25th 2012, 12:17 AM
biffboy
Re: Divisibility problem
I take 'evenly divisible by 25' to mean not the number itself. I take the question to mean what is the largest number that will divide into 5m+25 for all m.
• Jun 25th 2012, 12:34 AM
MikeNoob
Re: Divisibility problem
Quote:

Originally Posted by biffboy
I take 'evenly divisible by 25' to mean not the number itself. I take the question to mean what is the largest number that will divide into 5m+25 for all m.

I still dont get how they got
25 ?