# Solve Problems Involving the Calculation and Conversion of Units of Measure, Using Decimal Notation Up to 3 D.P. Where Appropriate

When solving problems involving calculation of units of measure, it is helpful to know our conversion facts.

When adding and subtracting mixed units of measure, it helps to convert our measures to the same units first.

When solving measure problems that involve multiplication or division, we don’t always need to convert our measures straight away. Often it is easier to do so after the calculation in order to give the answer in the correct unit of measure.

Example 1 => 4.25km + 1500m = ?
When adding mixed units of measure to solve a problem, it usually helps converting your measures to the same unit before calculating =>
4.25km + 1500m =4.25km + 1.5km = 5.75km

Example 2 => 7.5kg – 3250g = ?
When subtracting mixed units of measure to solve a problem, it helps to convert your measures to the same unit before calculating =>
7.5kg – 3250g =7.5kg – 3.25kg = 4.25kg

Example 3 => An empty case weighs 7000g. Izzy packs 14.125kg of clothing inside. How much does the suitcase now weigh in kilograms?
Solving an addition or subtraction measure word problem often needs a conversion first before a calculation.
7000g = 7kg.
14.125kg + 7kg = 21.125kg.

Example 4 => A small jar of fish food holds 15g. How much food would there be in 125 pots in kilograms?
With x and ÷ word problems, often it is not necessary to convert units before the calculation. We often need to convert our answers to the correct unit after the calculation.
15g x 125g = 1875g.
Converting to kg gives us an answer of 1.875kg.

Now try a few practice questions!

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