Why do this problem?
This excellent problem
is so very good for number awareness, and reinforcement of addition and subtraction rules.
Starting off in a very practical way with suitable rods would be ideal in many circumstances.
How did you get to this solution?
I see you've not got a (suppose - 9 when using 2,3 & 5) can you explain that?
What about four rods?
Which combinations work/do not work and why?