Question 252423
You can see we are adding a set of 10 odd numbers together. 10 odd numbers added together make an even number.

A quick review:

odd + odd = even

odd + odd + odd = odd

odd + odd + odd + odd = even

So, very quickly you can see if we add an odd number of odds, we get odd. Now, the question I believe wants you to add 5 odds to get 50. There is no way this can happen.

Don't know if you need a proof of this . . .