Check my work
You did the problem and the answer does not match. Paste what you did — this names the first line that goes wrong, what the error was, and carries on correctly from there.
How to use it
- 1
Paste your working, all of it
Every line, including the ones you are confident about. The check is looking for the first line that does not follow from the one above it, so it needs the line above it.
- 2
Include the original problem
On the first line. Without it there is nothing to check the first step against, and an error in the transcription of the question itself is a surprisingly common cause.
- 3
Read the flagged line
You get the line quoted back, the name of the error — sign, distribution, a dropped solution, an invalid cancellation — and then the corrected continuation. Everything before it is acknowledged as correct rather than re-derived.
Why this is the mode worth using
A finished solution tells you what the right method looks like. It does not tell you what you did instead, which is the thing you would need in order to stop doing it.
Finding the line where your working diverges is specific, memorable and transferable in a way that reading someone else's correct solution is not. If you are going to use one mode on this site while actually studying, use this one.
Errors it names
Sign errors after distributing a negative. Failing to apply an operation to every term. Cancelling across a sum rather than a factor. Squaring both sides and keeping the extraneous root. Losing the second solution of an even-power equation. Degrees where the formula wanted radians.
It also says when your working is right — including when a correct answer got there by a method that will break on the next problem, which is worth knowing before the next problem.
Errors it looks for
| Error | What it looks like | The fix |
|---|---|---|
| Sign error | -(x - 3) written as -x - 3 | Distribute the minus to every term |
| Partial operation | Dividing one side by 2 but only one term of the other | Whatever you do, do to the whole side |
| Invalid cancellation | Cancelling x from (x + 2)/x | You can cancel factors, never terms of a sum |
| Extraneous root kept | Squaring both sides and keeping both answers | Substitute each root back into the original |
| Lost solution | x^2 = 9 giving only x = 3 | An even power gives two roots |
| Degrees vs radians | sin(30) entered in radian mode | Check the mode the formula expects |
| Order of operations | 3 + 4 × 2 read left to right | Multiplication before addition, always |
Checking questions
- What if my working is actually correct?
- It says so in the first line rather than inventing a fault, and uses the rest to point out anything fragile about the method you used.
- Does it need my working typed out neatly?
- One step per line is enough. If it is on paper, photograph it — the photo path transcribes multi-line working too, and you can fix the reading before it checks.
- Will it tell me the answer?
- Yes, but after the diagnosis, not instead of it. The point of this mode is the line number.
- Is there a limit on how many problems I can do?
- There is no per-person limit and no account to run out of credits on. The site shares one daily AI allowance; on the rare day that runs out you are told so plainly, and it resets at midnight UTC.