As a way to get students to practice mental arithmetic, I compiled this Crack the Codes worksheet. The problems are graded from very easy to hard. Here are two examples:
1. Two Digit Number:
Reel B is an odd number. Reel A times reel B equals 24.
2. Three Digit Number:
Reel A has the highest digit. The answer is divisible by 5. Reel C has the lowest digit. The digits total 18.