Things You'll Need
Calculator on a Cell Phone
To figure out a tip at a restaurant. convert your percentage to a decimal and multiply it by your total bill. Your answer is the tip amount. For example, to figure out an 18 percent tip on a $32.74 bill, first convert 18 percent to .18. Multiply .18 and 32.74, and you will get a total value of 5.8932. Because money is only two decimal points, this tip will round to $5.89. To find the total bill, add $5.89 to $32.74. The total you will pay is $38.63.
To figure out a discount price. you will not only have to turn the percent into a decimal and multiply that decimal by the original price, but you will then need to subtract that percentage from the original price. For example, if you want to buy a pair of jeans that are $99 but are on sale for 30 percent off, first turn 30 percent to .3. Multiply .3 and 99
to get 29.7. Your discount will be $29.70. To find the sale price, subtract $29.70 from $99, and what you will actual pay at the register is $69.30.
To find a percentage change. such as a business' increase in profits from one quarter to the next, you will need to find the difference first, and then convert a decimal into a percent. First, calculate the change by subtracting the smaller number from the larger number. Then, divide the change by the original number. You answer will be a decimal, so you will have to change this decimal into a percentage by moving the decimal two places to the right. For example, if a business grossed $158,000 in the first quarter and $173,000 in the second quarter, find the difference. Subtract $158,000 from $173,000. Divide this change, $15,000 by the original, $158,000. Your decimal value will be 0.094936709. After moving the decimal two places to the right, your full percentage will be 9.4936709. You could also round this to 9.49 percent.