Using Percentages
Big sale: 75% off!! You see percentages all the time in sales (and if you pay any taxes!). Using percentages is like using decimals:
0.75 x 10 = 7.5
75% of 10 is 7.5
The easiest way to add percentages to your skills is to convert percentages into decimals by dividing by 100.
75% = 75%/100 = 0.75
Most people struggle with finding the cost of something after a discount. If a $10 hat is on sale for 75% off, then
You can use two strategies to find the hat’s cost when it’s on sale. First, you can subtract the discount:
- $10.00 – ($10.00 x 75%) = $10.00 – $7.50 = $2.50
With more experience, you can factor out the percentages and multiply once:
- $10.00 x 100% – ($10.00 x 75%) = $10.00 x (100% – 75%) = $10.00 x 25% = $2.50
The more second method takes more practice with percentages, but you will find that it’s easier to find a $35 shirt’s cost after a 10% discount as $35 x 90% and a $75 jacket’s cost after a 33% discount as 75 x 0.67.
Here are two videos to help you understand how to use percentages from Sal himself!
Finding Percentages
If you need to find a percentage, you are changing a fraction or a decimal into hundredths. You can think of this as a fraction with a denominator of 100 or a decimal to 2 places. Here is a great video explaining how to use equal fractions and long division to find percentages.
This longer video goes into the process finding and using percentages more in depth.
