Use the formula for an arithmetic series. That is, take the average of the first and the last number in the series, and multiply by 25. The first number in the series of course is 1; the last number is 1 + 2(24), since there are 24 intervals.
25
An odd number of odd numbers can not add up to an even number. There fore any 9 (odd) odd numbers can not add up to 50 (even).
35
55
Multiply two odd numbers Add an even and an odd Subtract an odd and an even
37
Can not be done! An odd number of odd numbers will ALWAYS add up to an odd number.
None. Any two odd numbers add up to an even number.
no
103
No three odd numbers can add up to an even number.
There are no such numbers. The sum of any three odd numbers must be odd. 112 is not.