# Measurement: Addition and Subtraction of km and m - Math

## Addition involving Length in Kilometres and Metres

#### Practice Question 1

The map below shows Mary's route. Let us use it to answer the question below:

Mary cycled from school to the shop through home. What distance did she cover?

Mary cycled 7 km 100 m.

- Start from the right: 600 m + 500 m = 1 100 m
- Convert 1 100 m to km: You get 1 km 100 m
- Write the 100 in the metres column and carry the 1 km into the kilometres column.
- Lastly, calculate: 4 km + 2 km + 1 km = 7 km.

#### Practice Question 2

The distance from Rachel's house to the market is 4 km and 400 m while the distance from the market to the church is 3 km and 800 m. What is the total distance from Rachel's house to the church, through the market?
- To understand the question being asked, start by drawing a rough sketch of the distances as shown below.

-Hence, the calculation will be:

Rachel travelled 8 km 200 m.

- Start from the right: 400 m + 800 m = 1 200 m
- Convert 1 200 m to km: You get 1 km 200 m
- Write the 200 in the metres column and carry the 1 km into the kilometres column.
- Lastly, calculate: 4 km + 3 km + 1 km = 8 km.

## Subtraction involving Length in Kilometres and Metres

#### Practice Question 3

Work out:

Answer is 7 km 150 m.

- Start from the right: 250 m - 100 m = 150 m
- Write the 150 in the metres column
- On the km column, calculate: 18 km - 11 km = 7 km

#### Practice Question 4

Work out:

Answer is 35 km 900 m.

- Start from the right: Since 134 m is smaller than 234 m, we borrow 1 km from the kilometres column.
- Remember that 1 km = 1000m, we convert the 1km we borrowed to m and add it to the 134 m on the right column: 1000 m + 134 = 1134 m
- Now calculate: 1134 m - 234 m = 900 m
- On the km column, remember that we borrowed 1 km, therefore we remain with 72 km - 1 km= 71 km
- Calculate, 71 km - 36 km= 35 km

#### Practice Question 5

A driver started a 55 km 40 m journey to a town. He got a puncture 40 km 60 m from his destination. Calculate the distance he covered before the puncture.

Answer is 14 km 980 m.

- Start from the right; the metres column: Since 40 m is smaller than 60 m, we borrow 1 km from the kilometres column.
- Remember that 1 km = 1000m, we convert the 1km we borrowed to m and add it to the 40 m on the right column: 1000 m + 40 = 1040 m
- Now calculate: 1040 m - 60 m = 980 m
- On the km column, remember that we borrowed 1 km, therefore we remain with 55 km - 1 km= 54 km
- Calculate, 54 km - 40 km= 14 km