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CRACK THE CODE · GRADE 1

Dinosaur Track Codebreaker

Find the secret numbers hidden behind the dinosaur footprints to reveal the four-digit combination.

Each shape stands for a number. Then solve the shape equations and read off the 4-digit code. Do it here or print the sheet — the answer key comes with it.

Print / download PDFMake another

The key

=2
=3
=8
=5

Every symbol is a whole number from 1 to 9.

Crack these

  1. 1.11−=
  2. 2.−=CODE 1
  3. 3.+=
  4. 4.+=CODE 2
  5. 5.+2=
  6. 6.+4=CODE 3
  7. 7.11−=
  8. 8.++=CODE 4
  9. 9.+?=11Which shape?
  10. 10.?+=5Which shape?

The vault code

Take the ones digit of your answers to problems 2, 4, 6, 8 (the ones tagged CODE 1–4), in that order. That opens the locked steel incubator.

Show answer key (for grown-ups)

Key: square = 2 · moon = 3 · pentagon = 8 · star = 5

Every symbol is a whole number from 1 to 9.

1.11 - moon8
2.moon - square1
3.star + pentagon13
4.pentagon + square10
5.square + 24
6.star + 49
7.11 - star6
8.star + square + pentagon15
9.moon + ? = 11pentagon
10.? + square = 5moon

Vault code: 1095

About Crack the Code

Crack the Code is early algebra without the letters: a key maps shapes to numbers, and the kid substitutes, computes, and — from grade 3 up — deduces hidden values from shape equations before they can solve anything. Grade 1 practices addition and subtraction within 20, and finding a missing shape. Every sheet has exactly one right key and one right code.

It's one of three things Math Mysteries makes, free and printable, personalized to what your kid is into: a full math mystery whodunit, a Lab Work sheet of multi-step word problems, or a Crack the Code sheet like this one. Browse free printable worksheets by grade, skill, and theme.

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