RedCrab Math Tutorial

# Percentage Calculation

Percentage calculation is certainly known to you, you will find it almost daily in your life. On this page some examples are described.
Starting point for the percentage calculation is the formula:

W is the percent value

G is the basic value

P is the percentage

## Calculate percent value

The first example calculates an increase of 3 percent. Whether it is a wage increase or rent increase does not matter and is left to your optimism or pessimism.
The percentage is given: P = 3. Let be the base value 1000, then G = 1000
We are looking for the percentage value W.
The formula is changed to the percentage value W.
The calculation is:
30 are added to the base value: 30 + 1000 = 1030 is the new amount

## Win and loss

Consider a package of shares worth 1000\$ and calculate the value of the shares when the price falls to 85%.
This means the percentage P = 85 with a base value G = 1000.
To calculate the percent value W, the formula is:
The value of the shares is now 850\$.

Suppose the stock price rises again by 15%, then we expect a base value of G = 850 and a percentage P = 15
The calculation is then:
The new value of the shares package is 850 + 127 = 977.50 \$. That's 22.50 \$ below the original value
The difference is due to the fact that we assumed a base value of G = 1000 when calculating the loss by 15%. When calculating the profit of 15% we assumed a base value G = 850.

## Calculate percentage

This example calculates what percentage of the stock value in the example above should have risen to reach the starting level of 1000\$.
The basic value G = 850 and the percentage W = 1000 are known
The formula is changed to:
The percentage of 1000\$ is therefore 117.65 percent of the initial value of 850\$. An increase of 117.65 - 100 = 17.65% is needed to reach the old starting value of 1000\$.

## Calculate basic value

Let's say you buy a product that is reduced by 60% for 120\$ and want to calculate the starting price. Thus, the percentage of 40% (100-60) that corresponds to a percent value of 120\$ is known.
We are looking for the basic value:
Note the wording. The goods were reduced by 60%; that means the remaining percentage is 40%. If the goods were reduced to 60%, the percentage would be 60%.

## Arithmetic

Integer and Real Numbers
Complex Numbers
Sets
Roots and Power
Percentage Calculation
Interest Calculation
Absolute Value of a Number
Euclidean division
Modulo - Remainder of a division
Vectors
Matrices