Word Problems Involving Decimals
When you get a word problem that involvesadding 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 1:
Joey, Keith, and Eli have a combined height ofmeters. If Joey ismeters tall and Eli ismeters 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 ofmeters. If Joey ismeters tall and Eli ismeters tall, how tall is Keith?
Now write the equation.
whereis the height of Keith in meters.
Combine like terms.
Subtractfrom each side.
Therefore, Keith ismeters tall.
This rewriting with the same number of digits may not be so important if the problem requires you tomultiply decimalsor 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... or worse!
Example 2:
James works at an Indian sweet shop. He needs to fill boxes withkilograms of coconut barfi each. If he haskilograms of coconut barfi, how many boxes can he fill?
This is a division problem: we need to find how many timeskilograms goes intokilograms.
Since the question asks for the number of boxes he canfill, the decimal part of the answer can be ignored. James can fillboxes, with a little bit of barfi left over.