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Current time:0:00Total duration:2:06

Video transcript

let's try to calculate thirty-nine point one minus zero point seven nine four and so pause the video and try this on your own alright I'm assuming you've given a go at it so now let's work through it together so I'm going to rewrite this it's thirty nine point one - I'm going to line up the decimals so that I have the right place values below the right place values - the zero is in the ones place so I'll put it in the ones place zero point seven nine four and now we're ready to subtract now how do we subtract four from nothingness here nine from nothingness here well the same thing is nothing the same thing as nothing is a zero and so now we can start to think about how to subtract well we still have the problem well we're trying to subtract four from zero so trying to subtract nine from zero so what we could do is take this 1/10 and try to regroup it into the hundreds place and the thousands place so let's think about this if we make this if we make actually that's not actually going to solve our problem well we could do it but then we're going to have zero tenths and we're still going to have a problem here so actually let me go to the ones place so let me get rid of a ones so that's eight ones which is going to be ten tenths so that's going to now we're going to have eleven tenths the ten tens from here plus one is eleven tenths now let's take one of those tenths so that we have ten tenths and give it to the hundredths so that's going to be ten hundredths and now let's take one of those hundredths so now we have nine hundredths and give it to the thousandths so that's going to be ten thousandths now we're ready to subtract so ten let me do this in yellow 10 minus 4 is 6 9 minus 9 is 0 10 minus 7 is 3 we have our decimal point 8 minus 0 is 8 and then we have 3 minus nothing is 3 so we're done thirty eight point three zero six