Math Checker: Find Wrong Sums in Any Text
Paste a forum post, receipt, set of notes or chatbot answer and this math checker reads every sum written with an equals sign. A green check means the stated answer is right. A red badge shows what the answer should be. It checks the arithmetic someone has already written down; it does not solve problems for you.
How to Check the Math in Your Text
- Paste or type your text into the box. It takes up to 10,000 characters.
- Look at the panel below the box. It repeats your text, with each stated answer highlighted and followed by a badge.
- Read the green and red counts above that panel, such as 3 correct and 1 wrong.
- Fix the text and the badges update as you type. Press Clear to empty the box and start over.
There is no Check button. Until a sum is found, a note under the box says No sums found yet, with an example to try: write 12 + 8 = 20 and a check mark appears beside the 20.
What the Badges Mean
| You write | Badge |
|---|---|
12 + 8 = 20 | Green check mark: the sum is right |
12 + 8 = 21 | Red badge showing 20, the real answer |
5 / 0 = 5 | Red badge reading Undefined |
40 x 12 = 470 | Red badge showing 480 |
A text can hold many sums. Several in one line or paragraph, bulleted or numbered lists, and sums inside ordinary sentences are all picked up, each with its own badge.
With a 20% tip, 13.50 + 20% = $16.20 (check mark).
We also counted 8 + 7 = 16 plates (red badge: 15).
What Sums It Understands
- Operators:
+-×÷*/^**, plus²and³ - Times as a letter:
3 x 4is read as 3 times 4, but only between figures - Brackets and implicit multiplication:
2(3+4) = 14 - Percentages:
200 + 10% = 220and50% * 80 = 40 - Currency signs:
$ € £ ¥and similar are ignored, so€10 + €5 = €15works - Number style: thousands separators and decimal commas follow the page's language, and full-width digits are read too
Rounded Answers and Chains of Sums
A stated answer that is rounded to the places it shows counts as right: 10 / 3 = 3.33 gets a check mark, because 3.33 is 10 / 3 rounded to two places. Write 10 / 3 = 3.4 and it is marked wrong.
A chain such as 2 + 3 = 5 = 10 - 5 is checked step by step, so each answer in the chain gets its own badge.
What It Leaves Alone
Anything it cannot check with certainty gets no badge, rather than a wrong one:
- Algebra with letters, such as
x = 5or2x + 3 = 7 - Numbers with units between them, such as
3 kg + 4 kg = 7 kg - Plain equalities like
5 = 5, and>=or<= - Functions such as sqrt or sin, and anything without an equals sign
For a quick answer to a single sum, the Expression Calculator works one expression at a time.
Private by Design
Your text is checked in the browser on your device. Nothing is uploaded or saved, and there is no account. Sums are read by a small built-in parser, not by running your text as code.
Math Checker FAQ
How can I check if my math is correct?
Paste the text into the box. Every sum written with an equals sign, like 12 + 8 = 20, gets a green check mark if the stated answer is right, or a red badge with the real answer if it is wrong. A summary under the box shows how many were correct and how many wrong.
Can I check math from ChatGPT or another AI answer?
Yes, for the arithmetic in it. Paste the AI's answer and each sum it wrote out, such as 17 * 3 = 41, is checked and marked. The tool only checks the calculations stated with an equals sign. It cannot tell whether the reasoning or the way a word problem was set up is right.
Does this math checker solve problems or show steps?
No. It checks answers that are already written in your text. It does not solve equations, work with letters like x, or show working. For a single expression you want calculated, use the Expression Calculator.
How do I check the totals on an invoice or receipt?
Paste the lines as text with the sums written out, for example 40 x 12 = 470, and each one is checked. Thousands separators and currency signs such as $ or € are ignored, so 1,200 + 350 = 1,550 reads correctly.
Why is 10 / 3 = 3.33 marked correct?
A stated answer rounded to the places it shows counts as right. 10 / 3 is 3.3333..., and 3.33 is that value rounded to two places. 10 / 3 = 3.4 would be marked wrong, with the real answer shown.
Why did a sum in my text get no badge?
Only sums with numbers on both sides of the equals sign are checked. Algebra with letters (x = 5, 2x + 3 = 7), numbers with units (3 kg + 4 kg = 7 kg), 5 = 5, >=, <=, functions like sqrt or sin, and lines with no equals sign are left alone.
Does it understand percentages and brackets?
Yes. 200 + 10% = 220 and 50% * 80 = 40 are both read as written, brackets are respected, and 2(3+4) counts as 2 times 7. Use ^ or ** for powers, and x, × or * for times between figures.
Is my text uploaded or stored?
No. The checking happens in your browser on your device. Nothing is uploaded or saved, and there is no account. The box accepts up to 10,000 characters.
Recommended
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TI-36X Pro Scientific CalculatorWorks through the multi-step homework answers and long chains the checker flags as wrong.
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Epson WorkForce ES-50 Portable ScannerScan a paper receipt or invoice so you can check its stated totals the same way.
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