The strategy
How it works
Recall a familiar fact, such as 5 × 6 = 30.
Use a pattern: double, halve, add a group, or swap the factors.
Say the related fact and check that the product makes sense.
See it in action
Worked examples
Example 16 × 7
- You may know 5 × 7 = 35.
- Add one more group of 7.
- 35 + 7 = 42.
Answer: 42
Example 28 × 4
- Double 4 to get 8.
- Double the product 4 × 4 = 16.
- 8 × 4 = 32.
Answer: 32
A quick heads-up
Common mistakes to avoid
- Mixing up a factor and a product; the product is the answer after multiplying.
- Assuming 6 × 7 and 6 + 7 are the same operation; multiplication counts equal-sized groups.
Your turn
Check your understanding
Choose an answer to see instant feedback and a short explanation. You can take the quiz again any time.
Question 1 of 3
What is 7 × 8?
7 groups of 8 make 56. One route is 7 × 4 = 28, then double.
If 5 × 6 = 30, what is 6 × 5?
Swapping the factors does not change the product: 6 × 5 = 30.
What is 9 × 4?
Think 10 × 4 = 40, then subtract one group of 4: 36.
Keep the momentum
Try a few practice problems
Choose a comfortable range and work through a short round with the free mental math trainer.