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

Welcome to Math with Mr. In this video, I'm going to cover how to calculate 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% 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 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 decimal. We can do this by moving the decimal twice to the left. It's as simple as that. So, for number one, 15% let's convert that to 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 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, 15 hundredths point 15 is the decimal form of 15%. Once we have that, we take our original price and multiply it by that decimal. So, our original price is $68 and we multiply that by 15 hundredths. Now, if you are using calculator and you have percent button, you can also use that. So, another way you can do this, you can do $68 times and make sure you hit the percent button. Don't do 68 * 15, do 68 * 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 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% 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 calculator as well. So, 68 dollars minus $10 and 20 cents. So, remember line up your decimals when you subtract decimals and then we are ready to subtract. 0 - 0 is 0. We need to borrow here. 10 - 2 is 8. Bring our decimal straight down. 7 - 0 is 7. And then 6 - 1 gives us 5. So, our final sale price is $57 and 80 cents. So, we took that 15% off of $68. Final sale price, $57 and 80 cents. Let's move on to number two where we have 40% off of $219.95. 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 percent button on calculator. So, let's do $219 and 95 cents. So, our original price times 40 hundredths or $219 and 95 cents times 40%. 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 dollars and 98 cents. So, I'll do this one by hand again. $219 and 95 cents. This is dollars minus $87 and 98 cents. So, this is dollars here as well. So, 5 - 8 in the hundredths place, well, we're going to need to borrow. So, we end up with 15 - 8, which is 7. 8 - 9, we need to borrow again. So, we have 18 - 9, which is 9. Decimal comes straight down. It's lined up throughout the entire problem. 8 - 7 is 1. 1 - 8, we need to borrow again. So, we have 11 - 8, which is 3. And then we have 1 in the hundredths place. So, $131 and 97 cents is our final sale price. So, we took 40% off of $219.95. So, there you have it. There's how you calculate discount and then use that discount to calculate the final sale price. hope that helped. Thanks so much for watching. Until next time, peace.