Subtraction of metres and kilometres

Group Activity 6

In pairs, find the length of the road that is not tarmacked.

1. To get the section not tarmacked, set the subtraction of 9 km 350 m from 4 km 160 m vertically.
2. First subtract the metres and write the results under the metres column.
3. Subtract the kilometres and write the results under the km column.
4. Discuss the results and share with other groups.

Example 5

The length of a road is 12 km 475 m. A section of the road 4 km 315 m long was tarmacked. What length of the road was not tarmacked?

$\begin{array}{cccc}& & \text{km}& \text{m}\\ \text{Length of the road}\hfill & & 12& 475\\ \text{Length of the road tarmacked}\hfill & \hfill –& 4& 315\\ \text{Length of the road not tarmacked}\hfill & & 8& 160\\ & & \end{array}$

Length of the untarmacked road is 8 km 160 m.

Group Activity 7

Mwandime covered 12 km 400 m in his journey. He covered 8 km 900 m by cycling and walked the rest of the journey.

1. Write the subtraction question vertically.
2. First subtract the metres, that is, 900 m from 400 m. What do you notice? Remember 1000 m is 1 km.
3. Regroup the metres and subtract.
4. Subtract 8 km from the remaining 11 km.
5. Discuss the results and share with other groups.