Full transcript of “How to Calculate a Discount without a Calculator | Calculating Discounts by Hand | Math with Mr. J”. Click a timestamp to open the video at that moment. Need another video? Use the YouTube transcript generator.
0:00 [Music] welcome to math with mr j [Music] in this video i'm going to cover how to calculate a discount by hand so we are going to write everything out without using a calculator this will show all of the steps for calculating a discount and then the final sale price based on that discount let's jump into our example where we have 35 percent off of 78.30 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
0:47 discount is in the form of a percent so we need to convert that percent to decimal form percent means per 100 so we divide our percent by 100 to convert it to a decimal we can do this by simply moving the decimal twice to the left so for our example let's move the decimal twice to the left to change it to decimal form so i'm going to rewrite 35 percent underneath here so i have enough room now 35 percent that's a whole number so our decimal comes at the end of a whole number we typically don't write it in there because we do not need it with it being a whole number let's move it twice
1:33 to the left once twice so it's going to come before the three so we have 0.35 that's our decimal form of 35 so once we have that we take our original price and 78.9 cents and multiply it by that rate of discount in decimal form so let's write that out 78 dollars and 95 cents times 35 percent in decimal form so 0.35 so let's calculate that and i'm going to come to the right in order to go through
2:18 those steps now when we multiply decimals we can take the decimals out and then place the decimal in the answer once we get to that point so i'm going to take the decimals out and multiply seven eight nine five times thirty five and again we will worry about the decimal at the end five times five is twenty-five five times nine is forty-five plus two is forty-seven five times eight is forty plus four is forty-four and then five times seven is thirty-five plus four is thirty-nine we are done with this five
3:06 and then the two four and four we need our placeholder zero because we are moving one place value to the left and now we can do three times five which is fifteen three times nine is twenty-seven plus one is twenty-eight three times eight is twenty-four plus two is twenty-six and then 3 times 7 is 21 plus 2 is 23 so now we add here 5 plus 0 is 5. 7 plus 5 is 12 1 plus 4 is 5 plus 8 is 13.
3:56 1 plus 9 is 10 plus 6 is sixteen one plus three is four plus three is seven and then we have a two so now we're ready to place our decimal so we look back at the original problem and see how many digits are to the right of a decimal or how many digits are behind a decimal well we have 1 2 3 4. so that's how many digits are going to be to the right of the decimal in our answer so we can count off one two three four digits our decimal is going to be placed in between the 7
4:42 and the 6 so we get let me rewrite this without the lines underneath so we get two 27.6325 now we are working with money so we need to round this to the hundredths place we have a three in the hundredths place look at the digit to the right we have a two that two says we stay the same so we are going to get 27 and 63 cents so 78 dollars and 95 cents times 0.35 i ran out of room here so i'm going to write it above that gives us 27
5:27 and 63 cents so that's our discount that's how much money we are taking off the original price that's 35 of 78. and 95 cents so once we have that information we can subtract that discount from the original price so the original price minus the discount we are taking the discount off of the original price the original price 78 95 and we are subtracting 27 63 so let's see what our sale price is
6:15 going to be now when we subtract decimals we need to line the decimals up so i'm going to calculate this to the right so we have 78 dollars and 95 cents minus 27.50 and 63 cents so the decimals are lined up and that's going to line up all of our places let's start by subtracting the hundredths so 5 minus 3 gives us two then we have nine minus six that's three we bring our decimal straight down it's lined up throughout the entire problem eight minus seven one and then seven minus 2
7:02 which is 5. so we get 51 32 so 51 and 32 cents so that is going to be our sale price so let me rewrite that 51 and 32 cents this is our final sale price 51 and 32 cents so there you have it there's how you calculate a discount by hand i hope that helped thanks so much for watching until next time peace
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