Question 1

What can this percentage calculator do?

Accepted Answer

Three jobs. (1) What is X% of Y — a 20% tip on $80 is $16. (2) X is what percent of Y — $16 of $80 is 20%. (3) X is Y% of what — $16 is 20% of $80. Same algebra, three directions. Results round to cents when the answer is money-shaped, and to two decimals when it is a percent.

Question 2

How do you calculate a percentage of a number?

Accepted Answer

Part = whole × (percent ÷ 100). That is the tip formula, the discount-off formula, and the “what is 7% sales tax” formula. Type the percent in the first box and the whole in the second.

Question 3

How do you calculate what percent X is of Y?

Accepted Answer

Percent = (part ÷ whole) × 100. If the whole is $0, there is no answer — dividing by zero is not a tip, it is an error, and we show that instead of inventing a rate.

Question 4

How do you find the original number from a percent?

Accepted Answer

Whole = part ÷ (percent ÷ 100). If a $12 tip was 15%, the bill was $80. If the percent is 0, there is no whole to recover.

Question 5

Is this the same as the discount or tip tools?

Accepted Answer

Same multiplication, different labels. Use Discount when you care about “was / now / you save.” Use Tip when you care about party size and pre-tax vs post-tax. Use this page when you just want the percent algebra without restaurant chrome.

Question 6

Do you handle percent change (from A to B)?

Accepted Answer

Not as a labeled mode. Percent change is ((B − A) ÷ A) × 100. You can do that in the second mode by treating (B − A) as the part and A as the whole. A dedicated percent-change tool is not this MVP.

Question 7

Why are some answers in dollars and some in percent?

Accepted Answer

Mode 1 and mode 3 return a number in the same units you typed (usually dollars). Mode 2 returns a percent. We do not assume currency. Type 200 people or 200 dollars — the math does not care.

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