To tell if your total will be even or odd can simply be worked out by knowledge of addition. If you add even numbers you'll always end up with an even total, but when we add odds the concept changes.
1 odd number addded to 3 even numbers will equal an odd number due to the fact the evens will equal an even number and you just add an odd on top, making it an odd. e.g. 12 + 12 + 12 = 36 + 11 =47 (odd number.)
2 odd numbers together equal an even number and adding that to an even you get an even. e.g. 11 + 23 = 34 (even.) 34 + 12 + 12 = 58.
3 odd numbers together equal an odd number , with the 2 equaling an even number it's like adding on the odd to make an odd number, but you still add on the even. e.g. 12 + 12 + 12 = 36 + 1 = 37 (even)
4 odd numbers added together would give you an even due to the fact 2 odds is even and when you add another 2 odds you also add an even, making an even.
e.g. 9 + 7 = 16 + 3 + 19 (which equals 22.) = 38.
In all a pattern seems to emerge showing us that...
1 odd = odd
2 odds = even
3 odds = odd
4 odds = even
The main pattern I found was that an odd amount of odds equals an odd number and an even amount of odds equals an even number.
Thank you for reading
Hazel