Doubling sprints: × 4 and × 8 — Speed Calculation

The fast method

Double up — “4 = 2 × 2 and 8 = 2 × 2 × 2”

1. × 4: double, then double again.
2. × 8: double three times.
3. To double a big number, double the tens and the ones separately and add: double 37 = 60 + 14 = 74.

Use it for: Packs of 4 or 8, perimeters of squares, and the 16 and 32 times tables.

Worked example: 37 × 8 = 296

✏️ 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”.

🏁 Lesson 6 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass — and beat the clock: finish within 3 min.

🏅 Sign in with Google to earn the 🚀 Rocket Multiplier badge when you pass — and a certificate when you finish all 5 lessons of Part 2 · Speed multiplying. You can still take the test without signing in.

🖨️ Multiply by 4 and 8 Worksheet

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