# GP formulas in math

## Calculate with percentages with the formulas

bettermarks »Math book» Algebra and functions »Assignments, percentages and interest» Percentage and interest calculation with the rule of three and formulas »Calculating with percentages with the formulas

In these explanations you will learn how you can use formulas to calculate a percentage, base or percentage value and how you can determine an increased or decreased base value.

### Apply formulas

You can use a formula to determine a percentage (p%), base value (G) or percentage value (W).
Percentage value:
Basic value:
of the 1,300 employees are female, they are female employees. formula
How many are from? W = ___ m
What percentage are of? p% = ___%
formula
How many grams was it in total if there are? G = ___ g

### Calculate increased or decreased base value

You can increase or decrease basic values ​​by a percentage by calculating the corresponding percentage value and then adding or subtracting it. Increased base value: Add the calculated percentage value to the base value. Decreased base value: Subtract the calculated percentage value from the base value. An increased or decreased base value can also be calculated directly. To do this, you have to multiply the old basic value by the appropriate factor. Factor for the increased base value: Factor for the reduced base value:
Base value G increased by p%: G
Base value G reduced by p%: G
Determine the reduced basic value with subtraction
Decrease by. Reduced base value: ___ km?
Determine the reduced base value
Reduced base value: km?
Determine the increased basic value with addition
Multiply. Increased basic value: ___ m
Determine increased basic value
Increased basic value: m

### Derivation of the formulas

The formulas for calculating the percentage, base and percentage value correspond exactly to the rule of three. The two steps from the rule of three table are combined here into one calculation step.
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