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# Multiplying numbers with different signs

## Video transcript

find the product four times negative five times negative seven point five so we're just multiplying three numbers right here some are positive some are negative we could actually do this in any order but let's just go left to right so let's start with the four times the negative five and then we'll multiply whatever we get there times negative seven point five so let's just rewrite the problem so we have four times negative five times negative seven point five I really don't have to write that dot there if you just have four and then a print in parenthesis in negative five that means four times negative five now the first thing you need to realize is that a positive times well a positive times a positive is obviously a positive a positive times a negative or a negative times a positive when you have different signs you're going to end up with a negative if you have same signs so even if you have a negative times a negative you're going to have a positive as well so let's just work that out in this problem so we have four times negative five four times five would be twenty let me do this in a different color so four times five would be 20 we have a positive times a negative so it's going to be a negative different signs mean we're going to have a negative so it becomes negative 20 times negative seven point five so let's figure out what that is we have to multiply 20 times 7.5 we could do that out here so 7.5 times 20 zero times five is zero zero times seven is zero put a zero here because we're obviously not going to multiply by two we're actually multiplying by 20 so 2 times 5 is 10 2 times 7 is 14 plus 1 is 15 and we get a 0 we get a 0 we get a 5 I'm just adding here either one and then you count the numbers you have behind the decimal point we only have one digit behind the decimal point in both numbers so you only go one digit behind the decimal point in our product so the answer here is 150 so this is equal to 150 and now we just have to think about is it going to be positive or negative we have a negative times a negative they are the same sign so it's going to result in a positive number so our final answer is 150 and if we actually wanted to keep the precision here we could write 150 point zero