Video: Dividing Integer Numbers Where Their Quotient Is a Decimal

18 ÷ 15= _.

02:26

Video Transcript

18 divided by 15 equals blank.

Let’s look at two different ways to do this division. First, we’ll put 18, the dividend, in a division box and put the divisor on the outside. And then we’ll ask, how many times can we divide 15 into 18? Well, we know that’s one. One times 15 equals 15, and 18 minus 15 equals three. At this point, we’re going to add a decimal at the end of the 18 and directly above it.

From there, we’re going to add a zero. 18 is equal to 18.0. And so, we haven’t changed the value of our dividend. We’ve just rewritten it. Then, we’ll bring down that zero and ask, how many times can 15 go into 30? 15 times two equals 30. And 30 minus 30 equals zero. This means that 15 goes into 18 1.2 times. 18 divided by 15, written as a decimal, is 1.2.

Let’s consider a second method. We could write 18 divided by 15 as a fraction, 18 over 15. And then, we could break the fraction up into two parts, 15 over 15 plus three over 15. We know that 15 over 15 equals one. So, we have one and three fifteenths. The one stays the same. But if we divide the numerator and the denominator by three, we can simplify three fifteenths to, say, one-fifth.

And now we want to write one and one-fifth as a decimal. The one stays the same. But if we multiply the numerator and the denominator by two, we’ll get the fraction two over 10, one and two-tenths. And we know that the fraction two-tenths, written as a decimal, is 0.2. So, we have 1.2. Our final answer for 18 divided by 15 is 1.2.

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