Word Problems Involving Decimals
When you get a word problem that involves adding or subtracting decimals, it's usually a good idea to rewrite all the numbers with the same number of decimal places, so you don't get confused.
Example:
Joey, Keith, and Eli have a combined height of 7 meters. If Joey is 2.31 meters tall and Eli is 2.6 meters tall, how tall is Keith?
First, rewrite all the numbers with the same number of decimal places.
Joey, Keith, and Eli have a combined height of 7.00 meters. If Joey is 2.31 meters tall and Eli is 2.60 meters tall, how tall is Keith?
Now write the equation.
2.31 + 2.60 + k = 7.00 where k is the height of Keith in meters.
Combine like terms.
4.91 + k = 7.00
Subtract 4.91 from each side. k = 2.09
Therefore, Keith is 2.09 meters tall.
This may not be so important if the problem requires you to multiply decimals or divide them. But in any case, you should check your answer at the end to make sure it makes sense. A small mistake can cause your answer to be off by a factor of ten or one hundred!
