Mental Addition Test
mediumFast mental addition is the foundation of all other mental maths. This test asks ten sums per round: Easy adds two 2-digit numbers, Medium adds two 3-digit numbers, and Hard adds three 3-digit numbers.
Two 3-digit numbers.
The tricks below show how to round, split and pair numbers so you rarely need to carry in your head, and the chart lists pairs that make 100.
Number pairs that make 100
| Number | Partner | Sum |
|---|---|---|
| 5 | 95 | 5 + 95 = 100 |
| 10 | 90 | 10 + 90 = 100 |
| 15 | 85 | 15 + 85 = 100 |
| 20 | 80 | 20 + 80 = 100 |
| 25 | 75 | 25 + 75 = 100 |
| 30 | 70 | 30 + 70 = 100 |
| 35 | 65 | 35 + 65 = 100 |
| 40 | 60 | 40 + 60 = 100 |
| 45 | 55 | 45 + 55 = 100 |
| 50 | 50 | 50 + 50 = 100 |
Tricks for faster mental addition
- Round and adjust: 49 + 38 = 50 + 38 − 1 = 87. For 198 + 247, add 200 and take away 2 to get 445.
- Add place by place, left to right: 346 + 289 = (300 + 200) + (40 + 80) + (6 + 9) = 500 + 120 + 15 = 635.
- Look for pairs that make 10, 100 or 1000. In 47 + 38 + 53, the 47 and 53 make 100, so the total is 138.
- Say the answer from the left. Most people read numbers left to right, so adding that way feels natural once you stop writing carries.
Frequently asked questions
What is 49 + 38?
Round and adjust: 49 + 38 = 50 + 38 − 1 = 87.
What is 346 + 289?
346 + 289 = (300 + 200) + (40 + 80) + (6 + 9) = 500 + 120 + 15 = 635.
How can I add numbers faster in my head?
Round and adjust: 49 + 38 = 50 + 38 − 1 = 87. For 198 + 247, add 200 and take away 2 to get 445. Look for pairs that make 10, 100 or 1000. In 47 + 38 + 53, the 47 and 53 make 100, so the total is 138.
What is 47 + 38 + 53?
47 + 53 = 100, then 100 + 38 = 138.
How is the speed maths test scored?
Each test has 10 questions. Answer 8 or more correctly to pass. Your time is recorded for the whole test, and your best time for each test and level is saved on your own device, so you can try to beat it.