How Do I Calculate the Percentage of Two Numbers?
To calculate the percentage between two numbers, determine the type of percentage needed. Then, subtract one number from the other, and divide it based on the type of percentage. Finally, multiply the answer by 100 to find the percentage.

Determine what type of percentage is needed
The percentage between two numbers is either a percentage change, error or difference. Change is used when comparing any two numbers, error is used when comparing an exact value to an estimated value, and difference is used to compare an old value to a new value. For example, if comparing the price of an item in two separate shops, percentage difference is used.

Subtract one value from the other
For percentage error and percentage change, use the absolute value of the answer when subtracting one value from the other. For example, if milk is $4.00 in one shop, but $5.50 in another, the difference is $1.50.

Find the percentage
For percentage change, divide the answer by absolute value of the old value; for percentage error, divide the answer by the exact value. For the percentage difference, divide the answer by the average of the two values. Once the final answer is calculated, multiply it by 100 to get the answer in percent. The percent difference for the two milk prices is $1.50 / (($4.00 + $5.50) * 0.5) * 100 = 31.6 percent.