The Proof! tabletop card game is the inspiration behind our free, online Math Puzzle Challenges. Each carefully constructed puzzle consists of a set of nine cards that hides a challenging equation. This is a hand-picked selection of our math games that focus specifically on subtraction. If you would like, you can create an account to save your progress. Or if you already have an account, you can log in.

39.
Find a Pair of 18's Using Only Subtraction
40.
Find 6 Different Pairs Less Than 0 Using Exactly 4 Cards Each
42.
Find 5 Different Quintuplets Greater Than 0
43.
Find Any Pair Less Than 100 Using All 9 Cards and No Square Roots
45.
Find 5 Different Pairs Greater Than 50 Using the 98, 64, and 16
47.
Find Any Pair Greater Than 0 Using All 9 Cards
49.
Find Any Pair Using Subtraction At Least 6 Times
50.
Find 2 Different Triplets Greater Than 10

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