Video: Subtracting Decimal Numbers in Word Problems

Use the table below to find out how many more people there are per square mile in Iowa than in Colorado.

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Video Transcript

Use the table below to find out how many more people there are per square mile in Iowa than in Colorado.

The first thing we need to do is find out how many people there are per square mile in Iowa and Colorado. In Colorado, there’re 41.5 people per square mile. In Iowa, there are 52.4 people per square mile. We know that 52.4 is larger than 41.5, but our question wants to know by how much. To do that, we’ll set up a subtraction problem 52.4 from Iowa minus 41.5 from Colorado.

Making sure that we carefully line up our decimal places, we subtract our 10ths from our 10ths. We need to subtract five 10ths from four 10ths, and that’s not possible. We can borrow from our units place, making the two in the units place a one. And then we add 10 10ths to our 10ths place. Instead of having four 10ths, we now have 14 10ths. And we can subtract five from 14. 14 minus five is nine. Bring down your decimal. We can now work with our units, and we have one minus one equals zero. In our 10s place, we have five minus four which is one.

52.4 minus 41.5 is 10.9. There are 10.9 more people per square mile in Iowa than in Colorado.