Relationship Between Volume, Capacity and Mass
Primary 6 · Mathematics
Relationship Between Volume, Capacity and Mass
Lesson 1 of 5
15 min
Let's begin
Ishimwe's family buys a 1.5 L bottle of drinking water. The nurse at the health centre told Ishimwe to drink about 1 500 mL of water every day. Is one bottle enough for a day? To answer, you need to know how litres and millilitres are linked.
The capacity of a container is how much liquid it can hold. The main units are the litre (L) and the millilitre (mL). A big bottle of water holds about 1 L. A teaspoon holds about 5 mL.
In the metric system each unit is 10 times the next smaller one:
| kL | hL | daL | L | dL | cL | mL |
|---|---|---|---|---|---|---|
| kilolitre | hectolitre | decalitre | litre | decilitre | centilitre | millilitre |
The facts you will use most:
From a bigger unit to a smaller unit, multiply. From a smaller unit to a bigger unit, divide.
Worked examples
2.5 L to mL: 2.5 × 1 000 = 2 500 mL.
750 mL to L: 750 ÷ 1 000 = 0.75 L.
3 L 250 mL to mL: 3 × 1 000 + 250 = 3 250 mL, which is also 3.25 L.
45 cL to mL: 1 cL = 10 mL, so 45 × 10 = 450 mL.
4 000 L to kL: 4 000 ÷ 1 000 = 4 kL.
So Ishimwe's 1.5 L bottle holds 1.5 × 1 000 = 1 500 mL. It is exactly enough for one day.
Worked example
A jug holds 1.2 L of juice. Keza pours 4 glasses of 250 mL each. How much juice is left?
Step 1: juice poured = 4 × 250 = 1 000 mL = 1 L.
Step 2: juice left = 1.2 L − 1 L = 0.2 L, which is 200 mL.
Worked example
How many 300 mL cups can you fill from a 1.5 L bottle?
Change to the same unit: 1.5 L = 1 500 mL. Then 1 500 ÷ 300 = 5 cups.
Tip
Going down the ladder to a smaller unit, the number gets bigger, so multiply. Going up to a bigger unit, the number gets smaller, so divide.
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