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: 9 3 2 6 − × ×
- A: 21
- B: 13
- C: 16
- D: 20
- E: 15 (the answer)
Why: 9 × 3 − 2 × 6 = 15. 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: 5 11 9 8 × × −
Your turn 2 of 3
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 6 12 10 11 + × ÷
Your turn 3 of 3
Use every number and every sign once (× and ÷ before + and −). Which answer can you make?
Numbers and signs: 1 4 9 7 − × ×
Keep practicing
Grown-ups: Play the 24 game or similar number games. Parent guide
Next lesson: Logic clues