Why WebAssign Marks a Correct Answer Wrong

The common reasons WebAssign rejects a right answer

You solved the integral, you got the right number, and WebAssign still marked it wrong. The frustrating part is that the grader isn't re-deriving your math — it's evaluating what you entered against rules the instructor configured for that question. When a correct answer gets a red X, it's usually one of these:

1. Significant figures — the value is right but the number of digits doesn't match what the question requires.
2. Tolerance — you rounded mid-problem and drifted outside the accepted band.
3. Units — the number is right but the unit is missing, extra, or in a form the question doesn't accept.
4. Syntax — a grouping error, a missing *, or the wrong scientific-notation format changed what you actually entered.
5. Re-submitting a green — you overwrote a correct part or burned an attempt.

Work down that list and you'll usually find the culprit. The rest of this guide takes each one in turn, then gives you the math-entry cheat-sheet so the syntax stops biting you.

Significant figures: a right value can still be marked wrong

This one stings because the value can be correct and you still lose the mark. When an instructor turns on significant-figure checking, WebAssign requires a specific number of significant figures — and per WebAssign's own documentation on answering numerical questions that check significant figures, an answer with the wrong number of significant figures is marked incorrect under that grading, even when the number itself is right.

The fix: match the significant figures implied by the given data. If the problem's inputs have three sig figs, give three — type 0.0123, not 0.012 and not 0.01234567. Watch trailing zeros: 2.50 and 2.5 carry a different number of sig figs. When you can't tell whether sig-fig checking is on, assume it is and match the data.

Tolerance and rounding: the mid-problem drift

WebAssign grades a numerical answer against the author's correct value within a tolerance the instructor sets, not against a single exact string. Per WebAssign's tolerance documentation, ordinary numerical questions commonly default to roughly ±2% relative tolerance, while questions using significant-figure grading typically allow about one unit in the last required digit. Both are configurable, and a strict instructor can tighten them.

That's why rounding early hurts: if you round π to 3.14 or clip an intermediate result, your final number can land just outside the band even though your method was right.

The fix: carry full precision through the whole calculation and round only at the very end. Keep constants symbolic (pi, e) as long as you can, and make the final rounding the only rounding you do.

Units and notation: the same number, rejected

The unit is part of the answer, and so is the way you write a power of ten. A few specific traps:

• Units count. Include the unit when the question asks for one. Depending on how the question is set up, an equivalent unit may be accepted, but a missing or mismatched unit is often marked wrong even with the right value.
• Scientific-notation format depends on the entry field. Some answer fields accept 6.022E23; others expect 6.022*10^23. The two aren't universally interchangeable, so if one form is rejected, try the other before assuming your value is wrong.
• Type words, not pasted symbols. Where the field takes typed formulas, enter infinity and pi rather than the ∞ or π symbols. Clicking those from the palette is fine; a pasted Unicode symbol often isn't.
• Multiplication usually needs an operator. 2x can read as a variable name; 2*x is unambiguous.

The syntax cheat-sheet (type math that parses)

WebAssign reads your input as a formula, not a picture, and evaluates it numerically or symbolically — so type it the way a calculator's text line wants. Use ^ for powers, / for division, and parentheses to group anything that belongs together. When in doubt, over-parenthesize: (a+b)/(c+d) is never ambiguous.

If a function won't type, open the palette (the mathPad, or the calcPad on calculus questions) and click it. Some questions intentionally restrict which functions you can use, so if a symbol won't take, check the palette for that question.

Preview, submit part by part, and leave greens alone

Never submit blind. When the question offers a preview, use it — it renders your input as real math notation, so you can confirm 1/2*x became the expression you meant and didn't read as 1/(2x). Five seconds of preview saves a wasted attempt.

Many WebAssign problems are multi-part, and parts are often submitted and graded independently, each drawing on your attempts. Work one part, preview it, submit it, and read the result before moving on. Once a part shows a green check, it's safest to leave it alone — re-submitting can waste an attempt or overwrite a right answer with a typo.

If you're running low on attempts, stop guessing: finish the problem fully on scratch paper, then type the final result once. That submit-and-check-per-part discipline is the same focus that helps you finish Canvas assignments fast when WebAssign is linked through your course.

Where Silent Student fits

Knowing every rule above helps, but WebAssign sets can still eat a whole evening, especially long banks that repeat the same steps with new numbers. If you'd rather automate the repetitive parts of homework, Silent Student works WebAssign sub-question by sub-question: it formats each answer for the field it detects, submits, and reads back WebAssign's result before moving on.

It's a signed desktop app for macOS and Windows made by Code Serpent LLC — not a browser extension. It syncs your courses, sorts everything by due date, and works the queue in the background while you focus elsewhere. It reaches WebAssign through your Canvas links or directly, and handles other courseware like Cengage MindTap and McGraw Hill the same way. You set a confidence threshold, and the bot records how sure it was on every answer; on a graded, single-attempt, untimed Canvas quiz, an answer below the threshold stops the quiz for your review. WebAssign itself submits as the solver goes. See how it works or compare plans starting at $11.99 a month.