Percentages

Because who can remember if it’s times or divide?

Getting a percentage of a number

10% of 200 | 20
25% × 200  | 50

Adding a percentage to or taking a percentage off a number

200 + 10%   | 220
10% on 200  | 220

200 - 10%   | 180
10% off 200 | 180

One number as a percentage of/on/off another number

20 is 10% of what   | 200
180 is 10% off what | 200
220 is 10% on what  | 200

Percentage ratios

If you know an amount and its percentage of a whole, you can find the percentage of another amount:

20% is 500, what is 750 → 30%

Or find the amount corresponding to another percentage:

if 20 is 30%, what is 60% → 40

Getting the change from one number to another, as a percent

50 to 75 is what %    | 50%
40 to 90 as %         | 125%

180 is what % off 200 | 10%
180 is what % on 150  | 20%

20 is what % of 200   | 10%
20 as a % of 200      | 10%

20/200 as %           | 10%
20/200 %              | 10%

Converting numbers and fractions to percentages

Note that 0.5 is 50%, 2 is 200%.

0.35 as %      | 35%
2/5 as percent | 40%
3/20 is what % | 15%
3 in 20 is what % | 15%

Calculations with mixed percentages & decimals

You can do calculations with pure percentages:

10% + 20% | 30%
90% − 40% | 50%

And you can add/subtract decimals & fractions to/from percentages. 1.0 is equivalent to 100%.

30% + 0.4      | 70%
100% - 1/2     | 50%
100% + 2 + 30% | 330%

Note that when multiplying a percentage by a number, the answer will always be a number (not a percentage), regardless of order:

50% × 30 | 15
30 × 50% | 15

Fractions

You can convert a decimal or a percentage to a fraction:

2/10 as fraction | 1/5
50% as fraction  | 1/2

You can also express a percentage as “1 in…” odds:

5% is 1 in what  | 1/20
40% is 1 in what | 1/2.5

The percentage in any of the percentage functions can also be replaced with a fraction:

2/3 of 600        | 400
50 is 1/5 of what | 250

Multipliers

Format a percentage (or fraction) as a multiplier:

20/5 as multiplier | 4x

The percentage in any of the percentage functions can also be replaced with a multiplier.

Use "x", "multiple" or "multiplier":

50 as x of 5         | 10x
2 as multiplier of 1 | 2x
2 as multiplier on 1 | 1x
1 as x off 2         | 0.5x

Getting the change from one number to another as a multiplier

50 to 75 is what x | 1.5x
20 to 40 as x      | 2x