How about: 120+1.2 = 121.2
31 & 67
1000 400 20 8
9 and 36
When you add two or more prime numbers you will only end up with a whole number and not a decimal number.
Add all of the numbers up, and then divide that result by how many numbers there were, e.g. 1,2,3,4,5. Added up they make 15. As there are five numbers there, you divide 15 by 5, and you get 3. Voila.
5
37 & 41
Pairs of prime numbers which add up to 82 are:3 + 7911 + 7123 + 5929 + 5341 + 41
I am not sure if any two consecutive numbers can add up to an even number.
The list of cubes are: 1,8,27 Which two numbers add up to 28? I think you can see which ones.
4 and 9.
16
13 & 17
1000 400 20 8
9 and 36
31 & 67
There is no pair of perfect squares that add up to 64.