Mental Math Trainer
Free timed drills for addition, subtraction, multiplication, division and remainders. No signup, works on any phone.
Mode
Numbers
Operations
Answers
- Pick the right answer from four options.
- Health drains 4 a second, and faster the longer you last.
- A correct answer gives health back, up to 50 for the hardest questions.
- A wrong answer costs 15.
- The run ends when health reaches zero.
Six ways to get faster
Every one of these replaces a hard step with an easier one. Try them while you drill: the point is to hold less in your head, not to think quicker.
1. Add from the left
Start with the big part of the number, then the small part. You keep one running total instead of a column of carries.
47 + 38
- 40 + 30 = 70
- 7 + 8 = 15
- 70 + 15
= 85
2. Round, then adjust
Numbers ending in 8 or 9 are easier as a round number with a small correction.
63 + 29
- 63 + 30 = 93
- that is 1 too many, so take 1 back
= 92
3. Subtract by counting up
Borrowing is the step people lose track of. Counting up from the smaller number avoids it completely.
82 − 57
- 57 up to 60 is 3
- 60 up to 82 is 22
- 3 + 22
= 25
4. Double and halve
Halving one number and doubling the other keeps the answer the same, and often turns a hard multiplication into an easy one. Multiplying by 5 is the same trick: take ten times the number, then halve it.
35 × 14
- halve 14 to get 7
- double 35 to get 70
- 70 × 7
= 490
5. Split the bigger number
Break one number into tens and units, multiply each piece, then add. This is the one that makes two-digit multiplication possible in your head.
23 × 7
- 20 × 7 = 140
- 3 × 7 = 21
- 140 + 21
= 161
6. Turn division around
Division is a times-table question in disguise. For a remainder, find the nearest multiple below the number and take the difference.
96 ÷ 6
- ask: 6 times what is 96?
- 6 × 16 = 96
= 16
47 mod 5
- the nearest multiple of 5 below 47 is 45
- 47 − 45
= 2
Questions people ask
What is a math trainer?
A drill that puts one arithmetic question in front of you after another and keeps score, so the facts you reach for most often become automatic. This one runs in your browser, with the operations and the size of numbers you choose.
Why is mental math so hard for me?
Because the method most of us learned works against the way memory works. Written arithmetic runs right to left and asks you to hold carries while you keep going. Working memory only holds a few things at once, so the numbers slip. Working left to right, or rounding and adjusting, leaves you with a single running total to remember instead.
How much practice actually helps?
A few minutes a day beats one long session a week. Speed comes from recall rather than cleverness: once 7 × 8 arrives without thinking, there is nothing left to hold on to, and bigger problems become a couple of small steps.
Do I need to know my times tables?
Up to 12 × 12 covers most of what these drills ask for. Anything larger can be split into pieces you already know, so those facts are the part worth drilling until they are automatic.
Is it free, and do I need an account?
It is free and there is nothing to sign up for or install. The drills run in your browser, on a phone as well as a laptop.
About this project
My Mental Math Trainer is a small, free practice tool. Pick the operations you want to work on, choose how big the numbers get, and answer as many as you can before the health bar runs out. There are no accounts and no ads.
It exists because most arithmetic drills are built for young children or sit behind a signup, and because getting quicker with numbers is mostly a matter of short, regular practice.