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

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%

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

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 multipler                                       | 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