Percentage calculator
Percent of a number, what percent one number is of another, change from one number to another, and add or remove a percent.
20% of 150 = 30
0.20 × 150 = 30
20% = 0.2 = 1/5
Difference (compared with the average)
Change vs difference
80 to 100 is +25%.
100 to 80 is −20%.
The average-based difference is 22.2%.
These are different questions.
+25% and −20% are the change from the first number to the second. 22.2% is a different question because it divides by the average.
Examples
Tip
15% of $45 is $6.75, total $51.75.
0.15 × 45 = 6.75
45 + 6.75 = 51.75
0.15 × 45 = 6.75 is mode 1, and the total is the bill plus the tip.
Price before a discount
A $120 price after 20% off was $150.
120 / 0.80 = 150
Type the sale price and 20% off. You do not have to know to type 80%.
The sale price and 20% off are enough, and 120 / 0.80 is the price before the discount.
45 out of 50
45 / 50 × 100 = 90
90% is the percent, and weights belong on the grade page.
A course grade is a weighted percentage. Use the grade calculator for weights and a final exam.