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Find the Missing Side is a free printable Grade 3 maths worksheet on working backwards from the area, aligned to Common Core standard 3.MD.C.7. It prints 8 questions with an answer key on its own sheet of paper, in 25 versions that each ask different questions, so no two pupils in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 21 of 25 · the same problems every time you open this link.

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Set 1 has all 25 in a single PDF. All 25 sets ask different questions.

Find the Missing Side

3.MD.C.7

NameDate

Work out the missing side.

1.
Area is 60, one side is 10. Other side =
2.
Area is 99, one side is 11. Other side =
3.
Area is 117, one side is 13. Other side =
4.
Area is 126, one side is 14. Other side =
5.
Area is 84, one side is 12. Other side =
6.
Area is 96, one side is 12. Other side =
7.
Area is 70, one side is 10. Other side =
8.
Area is 98, one side is 14. Other side =

LessonPrint · 3.MD.C.7 · Set 21 · free to copy for classroom use

Answer key — Find the Missing Side

Set 21. Prints on its own sheet.

  1. 1.6
  2. 2.9
  3. 3.9
  4. 4.9
  5. 5.7
  6. 6.8
  7. 7.7
  8. 8.7

Last reviewed 2026-09-05. Aligned to 3.MD.C.7 of the Common Core State Standards for mathematics.