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Main content
Current time:0:00Total duration:2:52

Video transcript

we're asked to multiply 32 point 1 2 or 32 and 12 hundredths times 0.5 or just 5/10 now when you multiply decimals you multiply them the exact same way you would multiply whole numbers and then you count the number of spaces behind the decimal you have in your two numbers you're multiplying and you're going to have that many spaces in your product and let me show you what I'm talking about so let's just multiply these two characters so we have 32 point one two times times 0.5 0.5 and when you write them out you can just push both of them all the way to the right you could almost ignore the decimal right now you can almost you should write the decimal where they belong but you can almost pretend that this is three thousand two hundred and twelve times five and then we'll worry about the decimals in a second so let's get started so if we were just multiplying 5 times three thousand two hundred and twelve we would say well five times two is ten regroup the 1 5 times 1 is 5 plus 1 plus 1 is 6 5 times 2 is 10 5 times 2 is 10 regroup the 1 and then finally you have 5 times 3 is 15 plus 1 is 16 is 16 and then we don't have any other places this 0 really isn't if we were just doing this as 0 5 we wouldn't multiply 0 times this whole thing we'd just get 0 anyway so just 5 times 3212 gives us this number but now we want to care about the decimals we just have to count the total number of spaces or places we have behind the decimal points in the two numbers we're multiplying so we have 1 2 3 spaces or 3 numbers to the right of the decimals and the two numbers were worth that we're multiplying so we need that many Speight numbers to the right of the decimal in our answer so you go 1 2 3 put the decimal right over there so 32.1 2 times 0.5 is 16 point 0 6 oh and this trailing 0 right here we can ignore because it's really not adding any information there so we could just write this as sixteen point zero six now the last thing you want to do is just kind of make sure that this makes sense you have a number that's almost 32 and we're multiplying it by 0.5 remember 0.5 is the same thing as 5 over 10 which is the same thing as 1/2 so we're really multiplying 32-point 1/2 times 1/2 we're trying to figure out what 1/2 of 32 point 1/2 is and well half of 32 is 16 and then 1/2 of 0.12 is 0.06 so this makes complete sense