There was a great deal in this problem and James has answered part of it:
Using only three rods with each one not exceeding 10 you can add and minus the following numbers which can go from 1-13.
The three numbers are 9, 3 and 1.
Well done James. Is 13 the largest number and why?
Can any of you help with some of the rest of the question:
In how many ways can you make 10?
What is the maximum number you can make with 4 rods?
Perhaps you can send in some more ideas.