Percent: sale price, tip, raise, share

How the page counts

• Percent means out of a hundred. 25% is 25 out of every 100.
• A percent of an amount is the amount times the percent, divided by 100. The page rounds it to the nearest cent, and says so when it had to round. It also shows the amount with that part taken off (a sale) and with it added (a tip, a tax, a raise).
• From one amount to another is the difference, divided by the amount before, times 100.
• One amount as a part of another is the part divided by the whole, times 100.
• A percent that does not come out even is shown to two places, with the word about.

Examples, worked by hand.

• A $40.00 shirt at 25% off: $40.00 × 25 ÷ 100 = $10.00 off. The price is $30.00.
• A tax of 8.25% on $19.99: $19.99 × 8.25 ÷ 100 = $1.649175, which rounds to $1.65. With it added: $21.64.
• An 18% tip on $42.50: $42.50 × 18 ÷ 100 = $7.65. With it added: $50.15.
• Rent that goes from $1,200.00 to $1,350.00 is up $150.00. $150.00 ÷ $1,200.00 × 100 = 12.5, so it went up 12.5%.
• Rent of $900.00 out of pay of $2,400.00: $900.00 ÷ $2,400.00 × 100 = 37.5, so rent is 37.5% of the pay.

The examples are made up. A program checks them, and 400 made-up sums counted a second way, every time the page is built.

Where percents trip people up

• Taking a percent off and adding the same percent back does not return to the start. $100.00 less 20% is $80.00. Add 20% to $80.00 and it is $96.00, because 20% of $80.00 is only $16.00.
• Two percents off, one after the other, do not add up. 20% off and then another 10% off turns $100.00 into $80.00 and then $72.00. That is 28% off, not 30%.
• Up and down are measured from different starts. $1,200.00 to $1,350.00 is up 12.5%. Going back, $1,350.00 to $1,200.00, is down about 11.11%, because the same $150.00 is measured against a bigger amount.
• A percent and a point are not the same. A rate that goes from 4% to 5% went up one point. One is a quarter of four, so the rate itself went up 25%.

What this page does not know

• It does not know any tax rate. You type the percent. A receipt, or the seller, shows the one that was used.
• It does not know what a tax is charged on: which things are taxed, and whether a coupon comes off before the tax or after.
• It does not know how a register rounds. The page rounds to the nearest cent, and half a cent goes up. A store may do it another way, so an answer can be a cent away from the receipt.
• It does not say what a tip, a price, a raise or a rent increase ought to be. It only does the sum.
• It holds up to 20 sums on this device, and they do not move to another phone or computer by themselves.

If the money does not cover the month

• On this site: Help with money has places to turn when the money does not cover the month, and Help with food is for when there is not enough to eat.
• Calling 211 reaches a local helpline in most of the U.S. that knows what help is near you.