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# Estimating decimal division

CCSS.Math:

## Video transcript

what we're going to do in this video is get a little bit of practice estimating dividing with decimals so for example we want to figure out approximately that's what these kind of squiggly equal sign means this means approximately equal so what is 80 divided by 1.9 for approximately equal so we want to estimate what this is so pause this video and see if you can figure it out so before we even look at these choices how would we try to do this in our head well we could say 1.9 4 it's hard to do that in our head to divide it into 80 but it's awfully close to 2 so we could say this is close to this is approximately equal to 80 divided by 2 because once again 1.9 4 is awfully close to 2 and then this is easy to figure out that is going to be equal to 40 so our first expression you could say is approximately equal to 40 is it exactly equal to 40 no but it's pretty close so I would select that choice let's do another one so pause this video and see if you can figure out the approximation what is 209 divided by 3 roughly equal to so once again here we don't have any clear decimals if we were to divide it out we would get a decimal answer for our quotient but what we could do is well it's either one of these is for example 209 is it close to a multiple of 3 that we might recognize well you might immediately recognize that well if you think about multiples of 3 you think in terms of well 3 times 6 is 18 3 times 7 is 21 well this is close to 210 so this is approximately equal to 210 divided by 3 now why is this interesting well 210 is just 21 times 10 so if 21 divided by 3 is 7 210 divided by 3 is going to be equal to 70 so once again 209 is pretty close to 210 remember we're just estimating and so 209 divided by 3 would approximately be equal to 70 which is that choice right over there let's do one more example so once again pause the video and figure out what six point eight six divided by 1.1 two is approximately equal to alright so here I would just try to round to the nearest whole number and see if that helps my division in my head so six point eight six is approximately seven if we round up to the nearest whole number and if I say seven divided by and if we round down one point one two seven divided by 1 this is much easier for us to do in our head so that is going to be seven now once again it's very important to realize these are estimations it's not going to be exactly equal to seven but it's definitely gonna be much closer to seven than 7,700 or seven thousand