Give your 12 year-old a step up on his friends. Let him or her grok negative addition and subtraction! Then, when they get a little older and learn Rust programming, they can tweak this to do whatever new math that needs practice!

Runs in terminal mode (run -> cmd, powershell, bash)

Written in Rust for blazing speed, cross platform, and reliablility.

Demonstration: Control-C to end. (like it was meant to be.)

$> target/debug/mathdrill.exe
1: 9 - (-6) = 15
Correct
2: 4 - (-9) = -6
   = 13
3: 1 - 7 = -6
Correct
4: -1 - (-4) = -5
   = 3
5: 6 - (-2) = 4
   = 8
6: 6 - 7 =   ^C

Send me your updates/pull request! (or let your 13 year-old do it as their first contribution to open source!)