Add and Subtract Different Units of Measure

In this activity, we are going to be adding and subtracting some measures.

We'll need to convert some measures as some objects may be in a different unit of measure.

We'll need to know these facts:

10 mm = 1 cm

100 cm = 1 m

1,000 m = 1 km

1,000 g = 1 kg

1,000 ml = 1 l

Let's get started:

           A                               B

Jug A has 2 litres of orange.

Jug B has 400 ml of orange.

How much orange is there altogether?

Answer:

In this question, we need to convert the units of measure so that they are the same.

We know that 1 l = 1,000 ml so 2 l = 2,000 ml

So jug A holds 2,000 ml

Jug A  = 2,000 ml

Jug B = 400 ml

2,000 + 400 = 2,400 ml

There is 2,400 ml of orange juice.

We could also convert this back to litres by dividing by 1,000.

2,400 ÷ 1,000 = 2.4 litres.

Let's have a look at another question:

The chair is 98 cm tall.

How tall would two chairs be?

In this question, we simply need to add 98 cm and 98 cm = 196 cm

Two chairs would measure 196 cm.

Let's have a look at one more question:

 The shopping bag weighs 1,100 g

4 apples weighing a total of 200 g are taken out.

What does the bag weigh now?

To answer this, we need to do a subtraction (subtract the weight of the apples)

1,100 - 200 = 900

The bag now weighs 900 g

Now it's your turn to have a go at some questions!