How many can you do in ninety seconds?
Straightforward arithmetic, one sum at a time, for ninety seconds. You type the answers, so guessing gets you nothing.
Ninety seconds. There is no way to pause, and the clock does not stop.
Before you start
- This measures how quickly you do arithmetic you already know how to do. It is not a test of mathematical reasoning — those are two different factors in the reference kit we work from, with different marker tests, and confusing them is the single most common way these scores get misread.
- You type the answer, so the floor is a true zero. Nothing here is multiple choice; a blind guess at a typed number is worth nothing, so every correct answer is a correct answer. That is a cleaner floor than four of our other tests have.
- This task may work without sight. Each sum is announced in a live region as it appears, the entry field is a real number input, and every control is reachable by keyboard. We have not tested it with a screen reader and will not claim it works until we have.
- Hiding this tab voids the attempt. Browsers slow timers in background tabs, which would hand you more than ninety real seconds. The rule is published below and it is enforced in the code.
Arithmetic test in progress
90s
Type the answer, then press Enter
Your result
What that says about the task
How the four operations went
What this task tested
How fast you carry out arithmetic you already know how to do. In the reference kit we work from, that is a factor in its own right — Number — and its marker tests are an addition test, a division test, and a subtraction-and-multiplication test. This is that factor, not a proxy for it.
This test is one of the seven arms of the Cognitive Fingerprint. It was not, until v2.0 — the Fingerprint shipped with four arms and arms were added in one deliberate version change once the domain set was complete, rather than one at a time, because the scores in a shared link travel in the link and adding an arm changes the answer a sent link resolves to. A link made when there were four arms is still read on the four-arm scale and keeps its number. How the number is built, and what the version marker does.
What this did not measure
It says nothing about whether you are good at mathematics. Working out which calculation a problem needs is a different factor with different marker tests, and people are routinely strong at one and ordinary at the other. That distinction is the whole of the companion page.
It also says nothing about arithmetic you do with a pen, or with a calculator, or without a clock. Ninety seconds of mental arithmetic on a screen is ninety seconds of mental arithmetic on a screen.
How much should you trust this number? What moved it that is not your arithmetic, what it legitimately supports, and what it cannot.
Things that moved this number that are not your arithmetic
- How fast you type. This is the big one and it is unavoidable in the format. Every answer has to be entered, so some part of this score is your hands and your keyboard. A test that removed typing would have to use multiple choice, which would put a floor under guessing and lose the clean zero — we chose the trade deliberately and we would rather name it than hide it.
- Which sums you happened to get. They are generated fresh each run, so two attempts are never the same set. That protects against learning the answers and it means some of the difference between two runs is simply which sums came up.
- Your day. Sleep, caffeine, interruptions, and whether you were rushing. Ninety seconds is short enough that a single lapse costs a measurable amount.
- Whether arithmetic is something you do. This is a practised skill more than most things we measure. Someone who does mental arithmetic daily will score higher than someone who has not since school, and that is a fact about practice rather than about capacity.
Should you believe this number?
What it legitimately supports: that in ninety seconds, on this screen, typing your answers, you completed this many sums correctly. That is a real measurement of a real thing and it is narrow on purpose.
What it cannot support: any statement about how you compare with other people. We have measured nobody, our reference sample is zero, and a count in a fixed window is exactly the kind of number that invites a percentile it has not earned.
Why your arithmetic score will not match another site's →
The rule we used is published in full further down this page, including the generator, the exclusions and the band boundaries. If you disagree with the number you can check the working and find where we differ.
Two questions, if you have twenty seconds
We are trying to find out whether explaining a result is worth doing at all. Nothing is recorded except which buttons you press — no result, no identifier, nothing that could be traced to you. There are no wrong answers here and nothing follows from your choice.
1 · Did the explanation above make sense to you?
2 · Did it tell you anything about yourself?
Recorded. Thank you — that is genuinely useful.
Comparing this run with another one
You do not have to write it down. Name the conditions for the run you just did and we will hold it on this screen while you do a second one.
What next
- Is being good at mental math a sign of intelligence? — the honest answer, and why a score you can train is a poor sign of anything you cannot.
- Why your arithmetic score will not match another site's — and why “good at maths” is two different things
- Build your Cognitive Fingerprint — the seven tests that make a shape, and the number they produce
- The instrument register — every test here with its version, its rung and its reference sample
- How BrainScore works — the norming ladder and where we sit on it
How this is scored
Published in full, because a score you cannot check is not worth much.
The task
- Ninety seconds. One sum at a time. Type the answer and press Enter, and the next one appears immediately.
- Four kinds of sum, in equal proportion: addition, subtraction, multiplication and division.
- Every answer is a whole number and never negative. Subtractions are built larger-minus-smaller, and divisions are built from a multiplication so they always come out exact. You will never be asked for a fraction or a decimal.
- A wrong answer costs you the item and nothing else. It does not subtract, and it does not end the run.
Where the sums come from
Generated fresh on every run, so there is nothing to learn between attempts. The ranges are published rather than described:
| Kind | How it is built | So the answer is |
|---|---|---|
| Addition | Both numbers from 2 to 49 | 4 to 98 |
| Subtraction | The smaller from 2 to 49, then 2 to 50 added to it to make the larger | 2 to 50, never negative |
| Multiplication | Both numbers from 2 to 12 | 4 to 144 |
| Division | An answer from 2 to 12 multiplied by a divisor from 2 to 12, then divided back | 2 to 12, always exact |
Verified before it shipped, not after. 200,000 generated items were checked against three rules: every answer is a whole number, no answer is negative, and the answer re-derived from the printed sum matches the answer the generator intended — that last one because a generator that prints one sum and marks a different one would be invisible to the first two. Zero defects. In that run the four kinds came out at 49,506 addition · 49,952 subtraction · 50,346 multiplication · 50,196 division, of 200,000 — the even split the generator intends. Counts rather than percentages, and the run they came from rather than a run in general, because the items are random and a different run gives different numbers.
The scoring rule
- Your score is the number of sums you answered correctly within the ninety seconds. That is the whole rule.
- Chance is zero, and that is unusual here. You type the answer rather than choosing one, so there is nothing to guess at — on four of our other tests a share of the score comes from luck, and on this one none of it does.
- The result also reports how each of the four operations went separately, because a person who is fast at addition and slow at division is not described by one number.
Exclusion rules — when an attempt does not count
- If the tab is hidden at any point during the window, the attempt is void. Browsers slow timers in background tabs, which would hand you more than the ninety real seconds the task allows. Checked when the run starts as well as when the tab changes, because a tab that was already in the background would never fire a change event.
- A run stopped early is scored on the seconds it actually covered, and the result says so. It is not scored as though the remaining time were wrong answers.
- A run abandoned by closing the tab is not scored at all; nothing is kept.
- Using a calculator would obviously change the number, and we cannot detect it and are not going to try. Nothing here is worth cheating for, and building surveillance into a test that stores nothing would cost more than it could ever be worth.
The bands
| Correct in 90s | What the result says about the task |
|---|---|
| 30 or more | At or past the pace this task was built around |
| 22–29 | A steady rate with little hesitation |
| 14–21 | Comfortable on some kinds of sum and slower on others |
| 7–13 | Working them out rather than recalling them |
| 0–6 | Few completed inside the window |
These boundaries are a design decision, not an empirical finding, and the top one is a declared number rather than a measured one: thirty correct is one sum every three seconds sustained for the full ninety. It is not derived from anyone's performance. This is the second declared ceiling on this site — the other is on symbol match — and both exist for the same reason: a rate has no natural maximum, so somebody has to choose one, and the honest thing is to say who chose it. When real data exists these will be revisited and the version will increment. The norming ladder, and where we are on it, is published in full.
What we do with your answers
Nothing. The test runs entirely in your browser. Your answers and your result are never sent to us and never stored. Closing the tab destroys them. The privacy notice covers this in full.
Sources
- Educational Testing Service. Kit of Factor-Referenced Cognitive Tests (1976 Edition). ets.org — the factor list, in which N — Number is marked by the Addition Test, the Division Test and the Subtraction & Multiplication Test, and is listed separately from RG — Reasoning, General. Read at source.