Broken Calculators

This calculator gets subtraction wrong the same way every time. Can your students crack its broken rule?

This calculator adds two-digit numbers wrong, the same way every time. Crack the rule, then predict its next mistake.

This calculator multiplies almost correctly. Students will find the one step it skips.

This calculator simplifies fractions with a rule that sometimes works. What is it doing wrong?

This calculator swears 0.5 is less than 0.45. What’s going on here?