If you want to calculate a percentage decrease, there are several mathematical formulas available.
The easiest method is to divide the decrease by the original number to determine the fraction of the original number you’re dealing with. For instance, if you start with 100 items and lose 20 of them, you can express this as a fraction (20 ÷ 100 = 0.2). Then, subtract this fraction from 1 (1 – 0.2 = 0.8) and multiply the result by 100 to obtain your percentage decrease (0.8 × 100 = 80%). Alternatively, you can use the formula [(Original Value – New Value) ÷ Original Value] × 100. For example: [(100 – 20) ÷ 100] × 100 = 80%.
Another method for calculate percentage decrease is by dividing the decrease by the original number. For example, if you have $100 and spend $30 on something, your percentage decrease would be 70% (which is calculated as 1 – (30/100) = 0.7). This method can be expressed using the formula [(Original Value – New Value) ÷ Original Value] × 100.
As you can see, there are various formulas for calculating percentage decreases. The choice between them depends on the specific context and what you intend to compare. For instance, the first formula is useful for comparing two values over time, such as when tracking the price of an item changing from $100 to $95, resulting in a 5% difference (calculated as (100-95)/100 = 5%).