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# Dividing a decimal by a power of 10

## Video transcript

we're asked to divide ninety nine point zero six one or ninety nine and sixty one thousandth by one hundred and there's a few ways to do it but I what I want to do in this video is focus on kind of a faster way to think about it and hopefully it'll make sense to you and that's also the focus of it that it makes sense to you so 99 let's just think about it a little bit so if we so ninety-nine point zero six one so if we were to divide this by ten just to make the point clear if we were to divide this by 10 what would we get well we would essentially move the decimal place one spot to the left and it should make sense because we have a little over 99 if you took 99 divided by 10 you should have a little over 9 so essentially you would move the decimal place one to the left when you divide by 10 so this would be equal to nine point nine zero six one if you were to divide it by a hundred so if you were to divide which is actually the focus of this problem so if we divide 99 point zero six one divided by 100 if we move the decimal place once to the left we're dividing by 10 to move it divide it by 100 divided by 10 again so we move it over twice so one two times and so now the decimal place is out in front of out in front of that first leading 9 which also should make sense 99 is almost 100 we're a little bit less than 100 so if you divide it by a hundred we should be a little bit less than one and so if you move the decimal place two places over to the left because we're really dividing by 10 twice if you want to think of it that way we will get the decimal in front of the 99 the point nine nine zero six one we should put a zero out here just sometimes it clarifies things so then we get this right over here now I want to think one way to think about although I do want you to always imagine that when you move the decimal place over to the left you really are dividing by 10 when you move it to the left when you move to the right you're multiplying by 10 sometimes people say hey look you could just count the number of zeros and if you're dividing so over here you were dividing by 100 100 has two zeros 100 has two zeros so and we're dividing by it so we can move our decimal two spaces to the left that's all right to do that is you know especially it's kind of a fast way to do it if you're you know if this had 2000 means let's say okay let's move the decimal 20 places to the left but I really want you to think about why that's working why that makes sense why it's giving you a number that seems to be to be the right kind of size number that this why why it makes sense that if you take something that's almost 100 and divide by 100 you'll get something that's almost 1 and that part frankly is just a really good reality check to make sure you're going the right direction with the decimal because Frank you know if you tried this 5 10 years from now maybe you're a little you your your memory of the rule or whatever you want to call it for doing it you're like hey wait do I move the decimal to the left or the right it's really good to do that reality check to say okay look if I'm dividing by 100 I should be getting a smaller value and moving the decimal to the left gives me that smaller value if I was multiplying by 100 I should get a larger value and moving the decimal to the right would give you that larger value