Most percentage mistakes are not arithmetic mistakes — they are answering a different question from the one asked. "20% of 1,500" and "20 is what percent of 1,500" look almost identical written down, and give 300 and 1.33% respectively.
So the questions are kept apart here, each with its own two fields and its own sentence. Pick the one that matches what you actually want to know.
No. ₱100 up 10% is ₱110; ₱110 down 10% is ₱99. The second percentage applies to the larger amount, so you end up below where you started. This catches people out constantly, and it is why a 10% discount never quite undoes a 10% price rise.
They are different questions with different answers. The first gives 300. The second gives 1.33%. They are kept as separate modes here precisely so they cannot be confused.
Because it is undefined. Going from 0 to 50 is an infinite increase — there is nothing to compare against. Returning "100%" would be a made-up answer, so the tool says so instead.
The last one divides by the magnitude of A, so a move from −100 to −50 reads as a 50% improvement rather than a 50% fall.
Arithmetic only — no rounding to currency. Nothing you type here is sent to our servers — the calculation runs entirely in your browser.
