If you are looking for a way to provide systematic fact fluency practice for addition and subtraction with sums up to 24, here it is! This goes through adding 0-12 to reach 24. and subtracting 0-12 from 24.
These problems reach sums to 24, such as 12+12, 11+12, 10+12, 9+12, etc. and And subtraction that begins at 24 and goes down to 12. 24-12, is the highest subtraction problem.
If you are looking for a program that stops at 20, that is a different set. You can find that linked below.