Doubles and halves game — Maths trick for kids

The trick

Split and double — “double the tens, double the ones, add”

1. Split the number into tens and ones: 37 = 30 + 7.
2. Double each part (30 → 60, 7 → 14) — or halve each part.
3. Add the two answers: 60 + 14 = 74.

Use it for: Sharing sweets fairly, doubling a recipe, and the × 4 and × 5 tricks.

Worked example: Double 37 = 74

✏️ Practice

Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.

🏁 Trick 5 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 🎈 Doubles Dazzler badge when you pass — and a certificate when you finish all 5 tricks of Part 1 · Finger & table tricks. You can still take the test without signing in.

🖨️ Doubles and Halves Trick Worksheet

• Worksheet set 1 (PDF)
• Worksheet set 2 (PDF)
• Worksheet set 3 (PDF)