# Length units, surface area and the calendar · Year 5

> Length units, surface area and the calendar, Year 5: Length units and more. Explanation, worked examples and free practice for the national curriculum in England.

In Length units, surface area and the calendar (Year 5) you practise 2 skills: Length units · The calendar.

The units of length are the kilometre (km), the metre (m), the decimetre (dm), the centimetre (cm) and the millimetre (mm). A kilometre is 1,000 metres; a metre is 10 decimetres or 100 centimetres; a decimetre is 10 centimetres; and a centimetre is 10 millimetres.

To change from a larger unit to a smaller one, multiply: 3 metres are 3 × 100 = 300 centimetres. To compare lengths written in different units, write them both in the same unit.

A cuboid has six rectangular faces, and each face is equal to the one opposite it. Its surface area is the sum of the areas of all six faces: 2 × (length × width) + 2 × (length × height) + 2 × (width × height). A cube has six equal square faces.

A common year has 365 days and 12 months. A week has 7 days, so 45 days are 6 weeks and 3 more days. To count the days from a date in one month to the same date in a later month, add up the days in the months that pass.

**Tip:** To find the surface area without missing a face, unfold the cuboid in your mind: three pairs of equal rectangles.

## What you learn

### Length units

- Example: How many metres are there in 9 km?
- Answer: 9000 m
- Solution: There are 1,000 metres in 1 km, so: 9 × 1,000 = 9,000

### The calendar

- Example: How many days are there in June in a common year?
- Answer: 30
- Solution: June has 30 days.

The exercises are made by rules and the answers are worked out in code. The topic follows the national curriculum in England: mathematics (key stages 3 and 4).

[Practise on the site](https://kixplo.com/uk/en/) · [All Year 5 topics](https://kixplo.com/uk/en/maths/year-5/)