Convert 45 mm into centimetres.

Recall the conversion fact: 1 cm = 10 mm Decide whether to multiply or divide: 45 ÷ 10 State the answer: 45 mm = 4.5 cm Answer: 4.5 cm

Convert 8.6 cm into millimetres.

Recall the conversion fact: 1 cm = 10 mm Multiply, because millimetres are smaller: 8.6 × 10 = 86 State the answer: 8.6 cm = 86 mm Answer: 86 mm

Convert 0.75 m into centimetres.

Recall the conversion fact: 1 m = 100 cm Multiply by 100: 0.75 × 100 = 75 State the answer: 0.75 m = 75 cm Answer: 75 cm

Convert 6500 m into kilometres.

Recall the conversion fact: 1 km = 1000 m Divide by 1000: 6500 ÷ 1000 = 6.5 State the answer: 6500 m = 6.5 km Answer: 6.5 km

Convert 250 mm into metres.

Recall the conversion fact: 1 m = 1000 mm Divide by 1000: 250 ÷ 1000 = 0.25 State the answer: 250 mm = 0.25 m Answer: 0.25 m

Unit conversion Worked Solutions — GCSE Maths

Fully worked, step-by-step solutions to GCSE Unit conversion questions. See exactly how to solve problems on metric length, mm to cm, cm to mm, m to cm.

metric lengthmm to cmcm to mmm to cmm to kmmm to m

GCSE Foundation70 questionsStep-by-step solutions

Question 1

1 markeasy

Convert

45\,\mathrm{mm}

into centimetres.

Worked solution

Recall the conversion fact
$1\,\mathrm{cm} = 10\,\mathrm{mm}$
There are $10$ millimetres in every centimetre.
Decide whether to multiply or divide
$45 \div 10$
Centimetres are the larger unit, so the number of them must be smaller — divide by $10$ .
State the answer
$45\,\mathrm{mm} = 4.5\,\mathrm{cm}$
Check by going back: $4.5 \times 10 = 45\,\mathrm{mm}$ .

Answer

4.5\,\mathrm{cm}

Question 2

1 markeasy

Convert

8.6\,\mathrm{cm}

into millimetres.

Worked solution

Recall the conversion fact
$1\,\mathrm{cm} = 10\,\mathrm{mm}$
Each centimetre is worth $10$ millimetres.
Multiply, because millimetres are smaller
$8.6 \times 10 = 86$
Going to a smaller unit makes the number larger.
State the answer
$8.6\,\mathrm{cm} = 86\,\mathrm{mm}$
Check by going back: $86 \div 10 = 8.6\,\mathrm{cm}$ .

Answer

86\,\mathrm{mm}

Question 3

1 markeasy

Convert

0.75\,\mathrm{m}

into centimetres.

Worked solution

Recall the conversion fact
$1\,\mathrm{m} = 100\,\mathrm{cm}$
There are $100$ centimetres in a metre.
Multiply by $100$
$0.75 \times 100 = 75$
Centimetres are smaller than metres, so expect a bigger number.
State the answer
$0.75\,\mathrm{m} = 75\,\mathrm{cm}$
Three quarters of a metre is $75\,\mathrm{cm}$ . Check: $75 \div 100 = 0.75\,\mathrm{m}$ .

Answer

75\,\mathrm{cm}

Question 4

1 markeasy

Convert

6500\,\mathrm{m}

into kilometres.

Worked solution

Recall the conversion fact
$1\,\mathrm{km} = 1000\,\mathrm{m}$
A kilometre is $1000$ metres.
Divide by $1000$
$6500 \div 1000 = 6.5$
Kilometres are the larger unit, so the number gets smaller.
State the answer
$6500\,\mathrm{m} = 6.5\,\mathrm{km}$
Check: $6.5 \times 1000 = 6500\,\mathrm{m}$ .

Answer

6.5\,\mathrm{km}

Question 5

1 markeasy

Convert

250\,\mathrm{mm}

into metres.

Worked solution

Recall the conversion fact
$1\,\mathrm{m} = 1000\,\mathrm{mm}$
A metre is $100\,\mathrm{cm}$ , and each centimetre is $10\,\mathrm{mm}$ , so a metre is $1000\,\mathrm{mm}$ .
Divide by $1000$
$250 \div 1000 = 0.25$
Metres are much larger than millimetres, so the number must shrink.
State the answer
$250\,\mathrm{mm} = 0.25\,\mathrm{m}$
A quarter of a metre. Check: $0.25 \times 1000 = 250\,\mathrm{mm}$ .

Answer

0.25\,\mathrm{m}

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