Lesson 2-9

percent formula

A = P x B A What = is P the percent x of B a number?

Simple Interest Formula

I = Prt I = Amount of Interest P = Principal (initial amount) r = Rate of Interest (as a decimal) t = time, in years

Discounts

If there is a percent discount on an item, subtract that percentage from 100 and then multiply by the price of the item - that is the percentage you will pay! Example: I have a 20% off coupon from Bed, Bath & Beyond. I want to buy a picture frame that is $14.99. How will I figure out the price? 14.99*0.8 because I'm paying for 80% of the picture frame!

Percent

Percent means per hundred. Percents are the result of expressing numbers as a part of 100. The percent sign, %, is used to indicate the number of parts out of 100 parts.

Total with sales tax

Remember that the cost of an item with sales tax includes 100% (1) of an item's price plus the sales tax percentage! Example: You are buying a shirt at Countryside Mall that costs $24.95 and the sales tax rate in Pinellas is 7%. How much will you pay for the shirt? Cost = 24.95 1.07

Sales Tax

Sales Tax Amount = Tax Rate x Item's Cost Example: If the local sales tax rate is 7.5% and a bike costs $394, what is the amount of sales tax that will be paid on the bike? Sales Tax = .075 x 394 = $29.55

fractions as percents

Step 1: Divide the numerator (top) by the denominator (bottom). Step 2: Move the decimal point 2 places to the right. Step 3: Add a percent sign.

percents as decimals

Step 1: Move the decimal point 2 places to the left. Step 2: Remove the percent sign.

decimals as percents

Step 1: Move the decimal point two places to the right. Step 2: Add a percent sign.

percent proportion

is over of = % over 100