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Grade 3 puzzle 5: Work backwards

A free grade 3 math puzzle that teaches Work backwards. Try it first — the hint and the full solution open when you are ready.

Problem 5 · Work backwards · 4 points

Made by AI and not reviewed by a real person.

I think of a number. I double it, then add 3, and I get 15. What was my number?

Illustration for problem 5
  1. 9
  2. 7
  3. 5
  4. 8
  5. 6
Show a hint
  • Undo the steps in reverse order: last step first.
Show the answer and solution

Answer: E — 6

Undo the "+3": 15 − 3 = 12. Undo the doubling: 12 ÷ 2 = 6. Working backwards — undoing each operation in reverse order — solves whole families of puzzles and is exactly how equations are solved.

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