Building equations
Strategy card
Build equations by working toward the target.
- Step 1: Estimate the size of the result.
- Step 2: Remember order of operations: × and ÷ before + and −.
- Step 3: Try the most likely operations first.
- Step 4: Compute each option exactly.
Tip: Parentheses change everything. Read them first.
Worked example
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 1 7 4 7 − × +
- A: 22 (the answer)
- B: 18
- C: 17
- D: 21
- E: 26
Why: 1 − 7 + 4 × 7 = 22. None of the other answers can be made with these numbers and signs.
Your turn
Your turn 1 of 3
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 2 1 6 2 − × +
Your turn 2 of 3
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 5 1 1 9 × ÷ +
Your turn 3 of 3
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 7 1 1 1 + × −
Keep practicing
Grown-ups: Play the 24 game or similar number games. Parent guide
Next lesson: Logic clues