In mathematics, the concept of percent change is used to describe the relationship between the old value and the new value. More specifically, the percentage change represents the difference between the old and new percentages as a percentage of the old value. Use formula ((V2 - V1) / V1) × 100, i.e. V1 represents the old or initial value and V2 reflect the new or current value. If the number is positive, it indicates a percentage increase and if it is negative, it indicates a percentage decrease. You can also use a modified formula to determine the percent decrease instead of using a negative number.
Step
Method 1 of 2: Using Standard Formulas
Step 1. Subtract the new value from the initial value
When calculating a percentage increase, the smaller number is the original (or old) number and the larger value is the new (or final) value. And vice versa, when you want to calculate the percentage decrease. You can use this formula to calculate a percentage increase or decrease. If your answer is a negative number instead of a positive number, the percentage will certainly decrease.
- For example, let's say you're trying to figure out how much your income has increased from one year to the next. If you made $37,000 last year and $45 this year, subtract 45,000,000 from 37,000,000 which makes 8,000,000.
- Otherwise, in the retail world, discounted products are usually written as “discount x%” which is a percentage decrease. If the pants previously sold for IDR 500,000 and now cost IDR 300,000, IDR 500,000 is the initial value and IDR 300,000 is the new value. To get started, subtract $300,000 from $500, which makes -$200,000.
Tip:
When you calculate a variable with more than one value change, find the percentage change for only the two values you want to compare.
Step 2. Divide the answer by the original value
After calculating the difference in values, divide the result by the initial number, which is a small number if the percentage increases, and a large number if the percentage decreases.
- Continuing the previous example, divide 8,000,000 (earnings difference) by 37,000,000 (which is the initial value). The answer is 0, 216.
- Otherwise, dividing the difference (-Rp200,000) by the old value (Rp500,000) is -0.40. One way of thinking about it is that the change of Rp200,000 in value is 0.40 from the starting point of Rp500,000, and the change value in the negative direction.
Step 3. Multiply the answer by 100
To convert an answer to a percentage, you just need to multiply the answer by 100. To convert it to a percentage, you just need to multiply it by 100.
- Take 0.216 and multiply by 100. In this case, the answer is 21.6 so your income increases by 21.6%.
- Otherwise, to get the final percentage, multiply the decimal answer (-0, 40) by 100. -0, 40 × 100 = -40%. This means that the new price of Rp. 300,000 pants is 40% less than the old price of Rp. 500,000. In other words, the pants are 40% off. Another way to think about it is that the $200,000 difference in price is 40% of the $500,000 initial price. Since the initial price is greater than the final price, give a negative symbol.
Method 2 of 2: Calculating Percentage Decrease in Other Ways
Step 1. Subtract the original value by the new value
To calculate the percentage decrease using this formula, subtract the larger value (original or initial value) by the smaller value (new or final value). Note that this is the reverse of how to find percentages using the standard equation.
For example, say you are trying to find out how much the number of new students changes each year. If the number of new students this year was 12,125 and last year was 13,500, subtract 13,500 from 12,125, to get 1,375
Step 2. Share the answers with the original scores
Remember that when specifying a percentage decrease, the original value is the larger number.
In this case, divide 1.375 (the difference between the two values) by 12.125 (the original value), which returns 0.1134
Step 3. Multiply the answer by 100
Convert the answer from decimal to percentage by multiplying it by 100.
Multiply 0, 1134 by 100, which is 11, 34. So, the number of new students decreased by 11, 34%
Tip:
If you use this equation and get a negative number, it represents a percentage increase.
