Banker's rounding (round half to even) reduces statistical bias in large datasets.
When to use this calculator
Reach for this calculator when you need a result you can act on confidently. The formula is straightforward, but manual computation introduces rounding errors that this tool eliminates entirely.
Common mistakes
A common mistake is applying the formula in the wrong direction — particularly with percentage and ratio problems, where the part and the whole can be mistakenly swapped. Check which value is the reference (the 'whole') before entering inputs.
Real-world scenarios
A student checks their overall module grade before results day: 3 assignments scored 72%, 68%, and 81% — the calculator confirms the weighted average and tells them what score they would need on the final exam to achieve a target grade.
Frequently asked questions
How do you round to 2 decimal places?
Look at the third decimal digit. If 5+, round up; if under 5, keep the second digit. 3.456 → 3.46.