How to Calculate a Discount and Sale Price | Math with Mr. J

[Music] welcome to math with mr j [Music] in this video i'm going to cover how to calculate a discount and then the final sale price based on that discount let's jump into our examples and see exactly how we do this starting with number one where we have 15 percent off of 68 now the first thing that we need to do is to calculate the discount so how much money will be taken off the original price we do this by multiplying the original price by the rate of discount the rate of discount is going to be in the form of a percent so we want to get that percent to decimal form percent means per 100 so we divide the percent by 100 to convert it to a decimal we can do this by moving the decimal twice to the left it's as simple as that so for number one fifteen percent let's convert that to a decimal so move the decimal twice to the left that's going to divide that percent by 100 and give us the decimal form so for a whole number the decimal comes at the end so let's put our decimal in there and then move it once and then twice to give us our decimal form so fifteen hundredths point one five is the decimal form of fifteen percent once we have that we take our original price and multiply it by that decimal so our original price is 68 dollars and we multiply that by fifteen hundredths now if you are using a calculator and you have a percent button you can also use that so another way you can do this you can do sixty eight dollars times 15 and make sure you hit the percent button don't do 68 times 15 do 68 times 15 so both of those problems there are equivalent and will give you the same correct answer so once we solve that we're going to get 10 dollars and 20 cents so both of these are going to give us 10 and 20 cents so that's our discount that's how much money we are going to get off of the original price that's 15 percent of 68. so now we need to take the original price of 68 and subtract the discount that will give us our final sale price so i'm going to do this by hand you can obviously do it with a calculator as well so 68 dollars minus ten dollars and twenty cents so remember line up your decimals when you subtract decimals and then we are ready to subtract zero minus zero is zero we need to borrow here ten minus two is eight bring our decimal straight down seven minus zero is seven and then six minus one gives us five so our final sale price is fifty seven dollars and eighty cents so we took that fifteen percent off of 68 final sale price 57 and 80 cents let's move on to number two where we have 40 percent off of 219 and 95 cents so we have two ways here we can do decimal form so move the decimal twice to the left one two or we can use a percent button on a calculator so let's do 219 dollars and 95 cents so our original price times 40 hundredths or 219 dollars and 95 cents times 40 percent both of those will give us the correct discount and that is going to be 87 so let's put our dollar sign here 87 and 98 cents so 87 and 98 cents so once we have that that's our discount the money off we can take it off of our original price so the original price minus that discount of 87. and 98 cents so i'll do this one by hand again 219 dollars and 95 cents this is dollars minus eighty-seven dollars and ninety-eight cents so this is dollars here as well so five minus eight in the hundredths place well we're going to need to borrow so we end up with 15 minus 8 which is 7. 8 minus 9 we need to borrow again so we have 18 minus 9 which is 9 decimal comes straight down it's lined up throughout the entire problem 8 minus 7 is 1. 1 minus 8 we need to borrow again so we have 11 minus 8 which is 3 and then we have a 1 in the hundreds place so 131 and 97 cents is our final sale price so we took 40 off of 219 and 95 cents so there you have it there's how you calculate a discount and then use that discount to calculate the final sale price i hope that helped thanks so much for watching until next time peace