Year 6 Arithmetic (SATs): Miles, kilometres and imperial approximations
Part of the Year 6 Arithmetic (SATs) measures and conversions chapter. Chapter overview · whole chapter on one page
Miles, kilometres and imperial approximations
Rule
These are approximate equivalences, so use the word "about" when you give an answer:
8 km is about 5 miles. 1 inch is about 2.5 cm. 2 pounds is about 1 kilogram. 2 pints is about 1 litre.
To change km to miles, divide by 8 and multiply by 5. To change miles to km, divide by 5 and multiply by 8.
Key ideas
- 8 km is about 5 miles.
- Divide by 8 then multiply by 5 to change km to miles.
- Give imperial conversions as "about", because they are rough.
Method. Divide by 8, then multiply by 5.
- Divide by 8. 40 ÷ 8 = 5 lots of 8 km.5
- Multiply by 5. Each 8 km is about 5 miles, so 5 × 5 = 25.25 miles
- Write the answer. about 25 miles
Check. 40 km is about 25 miles, because 8 km is about 5 miles. ✓
Method. Multiply by 2.5, because 1 inch is about 2.5 cm.
- Use the fact. 1 inch is about 2.5 cm.2.5 cm
- Multiply. 10 × 2.5 = 25.25 cm
- Write the answer. about 25 cm
Check. 25 cm ÷ 2.5 = 10 inches. ✓
Method. Use 2 pounds is about 1 kilogram, so multiply by 2.
- Use the fact. 1 kg is about 2 pounds.2 pounds
- Multiply. 6 × 2 = 12.12 pounds
- Write the answer. about 12 pounds
Check. 12 pounds ÷ 2 = 6 kg. ✓
Exercise 8C Practice: miles, kilometres and approximate equivalences
Non-calculatorMethod. Divide by 8, then multiply by 5.
- Divide by 8. 24 ÷ 8 = 3.3
- Multiply by 5. 3 × 5 = 15.15 miles
- Write the answer. about 15 miles
Check. 15 miles is about 24 km, since 5 miles is about 8 km. ✓
Method. Divide by 8, then multiply by 5.
- Divide by 8. 64 ÷ 8 = 8.8
- Multiply by 5. 8 × 5 = 40.40 miles
- Write the answer. about 40 miles
Check. 40 miles is about 64 km, since 5 miles is about 8 km. ✓
Method. Divide by 8, then multiply by 5.
- Divide by 8. 80 ÷ 8 = 10.10
- Multiply by 5. 10 × 5 = 50.50 miles
- Write the answer. about 50 miles
Check. 50 miles is about 80 km, since 5 miles is about 8 km. ✓
Method. Divide by 8, then multiply by 5.
- Divide by 8. 16 ÷ 8 = 2.2
- Multiply by 5. 2 × 5 = 10.10 miles
- Write the answer. about 10 miles
Check. 10 miles is about 16 km, since 5 miles is about 8 km. ✓
Method. Divide by 8, then multiply by 5.
- Divide by 8. 56 ÷ 8 = 7.7
- Multiply by 5. 7 × 5 = 35.35 miles
- Write the answer. about 35 miles
Check. 35 miles is about 56 km, since 5 miles is about 8 km. ✓
Method. Divide by 5, then multiply by 8.
- Divide by 5. 15 ÷ 5 = 3.3
- Multiply by 8. 3 × 8 = 24.24 km
- Write the answer. about 24 km
Check. 24 km is about 15 miles. ✓
Method. Divide by 5, then multiply by 8.
- Divide by 5. 25 ÷ 5 = 5.5
- Multiply by 8. 5 × 8 = 40.40 km
- Write the answer. about 40 km
Check. 40 km is about 25 miles. ✓
Method. Divide by 5, then multiply by 8.
- Divide by 5. 50 ÷ 5 = 10.10
- Multiply by 8. 10 × 8 = 80.80 km
- Write the answer. about 80 km
Check. 80 km is about 50 miles. ✓
Method. Multiply by 2.5.
- Multiply. 4 × 2.5 = 10.10 cm
- Write the answer. about 10 cm
Check. 10 cm ÷ 2.5 = 4 inches. ✓
Method. Multiply by 2.
- Multiply. 5 × 2 = 10.10 pounds
- Write the answer. about 10 pounds
Check. 10 pounds ÷ 2 = 5 kg. ✓
Method. Multiply by 2, because 1 litre is about 2 pints.
- Multiply. 3 × 2 = 6.6 pints
- Write the answer. about 6 pints
Check. 6 pints ÷ 2 = 3 litres. ✓
Method. Divide by 2.
- Divide. 10 ÷ 2 = 5.5 litres
- Write the answer. about 5 litres
Check. 5 × 2 = 10 pints. ✓
Method. Divide by 5, then multiply by 8.
- Divide by 5. 15 ÷ 5 = 3.3
- Multiply by 8. 3 × 8 = 24.24 km
- Write the answer. about 24 km
Check. 24 km is about 15 miles. ✓
Method. Divide by 2.5, because 1 inch is about 2.5 cm.
- Divide. 20 ÷ 2.5 = 8.8 inches
- Write the answer. about 8 inches
Check. 8 × 2.5 = 20 cm. ✓
Method. Use the fact that a mile is longer than a kilometre.
- Check the fact. 1 mile is about 1.6 km.1.6 km
- Compare. 5 km is about 3 miles, not 8.3 miles
- Write the answer. Because 1 mile is about 1.6 km, so 5 miles is about 8 km, while 1 km is less than a mile, so 5 km is about 3 miles.
Check. 5 × 1.6 = 8, and 5 ÷ 1.6 is about 3. ✓