How to reverse a percentage: X is P% of what?
✓ Verified in LibreOffice 25.8.7.3You know the part and the rate — recover the whole. Deposits, samples, partial payments.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =A2/B2 | A2 = the known part, B2 = the rate it represents (15% stored as 0.15). |
| Google Sheets | =A2/B2 | Identical. |
| LibreOffice Calc | =A2/B2 | Identical. |
How it works
If 12 is 15% of something, the something is 12 ÷ 0.15 = 80 — part over rate gives the whole, because part = whole × rate rearranged. The everyday cases: a $500 deposit that's 20% of the job (500/0.2 = $2,500 total), 45 survey responses at a 9% response rate (500 sent). Kin to the before-a-discount recipe — reverse percentage problems always divide, never multiply.
Verified, not just documented
We ran =A2/B2 in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 80 — exactly the expected result. Every formula here is confirmed by actually executing it.