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Broken Calculators

Broken Calculator: 2-Digit Subtraction

Broken Calculator: 2-Digit Subtraction

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

Broken Calculator: Multiplication Cross Product

Broken Calculator: Multiplication Cross Product

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

Broken Calculator: 2-Digit Addition

Broken Calculator: 2-Digit Addition

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

Broken Calculator: Simplifying Fractions

Broken Calculator: Simplifying Fractions

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

Broken Calculator: Comparing Decimals

Broken Calculator: Comparing Decimals

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