Convert Metric Units of Length

Convert Metric Units of Length exercise

• Can you complete the table?

  Hints

  Recall the abbreviations:

  • km = kilometres
  • m = metres
  • cm = centimetres
  • mm = millimetres

  To find the number of metres in 1 kilometre, multiply 1 by 1,000.

  To find the number of centimetres in 1 metre, multiply 1 by 100.

  To find the number of millimetres in 1 centimetre, multiply 1 by 10.

  Solution

  1 km (kilometre) = 1,000 m

  1 m (metre) = 100 cm

  1 cm (centimetre) = 10 mm (millimetres)

• Can you find the equivalent lengths?

  Hints

  Remember:

  1 km (kilometre) = 1,000 m

  1 m (metre) = 100 cm

  1 cm (centimetre) = 10 mm (millimetres)

  If you are converting from a smaller unit to a larger unit, use division.

  • 200 cm to m - divide 200 by 100 to get 2 m.

  If you are converting from a larger unit to a smaller unit, use multiplication.

  • 2 m to cm - multiply 2 by 100 to get 200 cm.

  For example, if we are looking for a matching pair for 400 mm, we can divide 400 by 10 to convert to cm.

  400 $\div$ 10 = 40

  As another example, if we are looking for a matching pair for 80 cm, we can multiply 80 by 10 to convert to mm.

  80 x 10 = 800

  Solution

  • 400 mm = 40 cm 400 $\div$ 10 = 40
  • 80 cm = 800 mm 80 x 10 = 800
  • 4 m = 400 cm 4 x 100 = 400
  • 8 km = 8,000 m 8 x 1,000 = 8,000
  • 8,000 mm = 800 cm 8,000 $\div$ 10 = 800

• Can you convert the lengths?

  Hints

  Remember:

  1 km (kilometre) = 1,000 m

  1 m (metre) = 100 cm

  1 cm (centimetre) = 10 mm (millimetres)

  To convert metres to centimetres, multiply by 100.

  To convert metres to kilometres, divide by 1,000.

  To convert centimetres to millimetres, multiply by 10.

  Solution

  Peter measured the length of his garden to be 12 metres. This would be 1,200 centimetres.

  • Multiply 12 by 100 to convert 12 metres to 1,200 centimetres.

  ${}$

  Logan is running 5 kilometres for charity. This is 5,000 metres.

  • Divide 5,000 by 1,000 to convert 5,000 metres to 5 kilometres.

  ${}$

  The pencil is 190 millimetres. This is 19 centimetres.

  • Multiply 19 by 10 to convert 19 centimetres to 190 millimetres.

• Can you put the lengths in order?

  Hints

  Convert all lengths to the same unit to make comparison easier.

  Remember:

  1 km (kilometre) = 1,000 m

  1 m (metre) = 100 cm

  1 cm (centimetre) = 10 mm (millimetres)

  For the first set, convert all length to millimetres by multiplying the lengths in centimetres by 10.

  You can then order these lengths: 120 mm, 145 mm, 100 mm (10cm), 120 mm and 130 mm (13 cm).

  Solution

  1.10 cm, 120 mm, 13 cm, 140 mm, 145 mm

  If we convert all lengths to mm (by multiplying lengths in centimetres by 10), we get:

  • 100 mm (10 cm x 10)
  • 120 mm
  • 130 mm (13 cm x 10)
  • 140 mm
  • 145 mm

  _________________________________________________

  2.1,000 m, 2 km, 2,200 m, 2,700 m, 3 km

  3.1 m, 114 cm, 1,400 mm, 2 m, 201 cm

• How many metres is 600 centimetres?

  Hints

  1 m = 100 cm

  To convert centimetres (cm) to metres (m), divide by 100.

  For example, if we were converting 700 cm to m, we would divide 700 by 100.

  700 $\div$ 100 = 7

  700 cm = 7 m

  How many metres in 600 cm?

  Solution

  The correct answer is 6 m.

  To convert centimetres to metres, we divide by 100.

  600 $\div$ 100 = 6

• What could the length be?

  Hints

  Convert all of the lengths in the question to metres to work out the range of possible answers.

  • 5 km = 5,000 m
  • 12,000 mm = 12 m
  • 3, 800 m = 3,800 m
  • 2,100 cm = 21 m

  We can now see that possible answers will fall between 21 m and 3,800 m.

  Convert the possible answers to metres, which ones fall between 21 and 3,800 m?

  There are 4 possible answers.

  Solution

  The possible answers are:

  • 2,200 cm
  • 3 km
  • 395 m
  • 2,900 m

  If we convert all of the measurements in the question to metres we get:

  • 5 km = 5,000 m
  • 12,000 mm = 12 m
  • 3,800 m = 3,800 m
  • 2,100 cm = 21 m

  From this, we can see that possible answers will fall between 21 m and 3,800 m. If we convert the correct possible answers to metres, we get:

  • 2,200 cm = 22 m
  • 3 km = 3,000 m
  • 395 m = 395 m
  • 2,900 m = 2,900 m

  The incorrect answers convert to:

  • 220 cm = 2.2 m
  • 4 km = 4,000 m
  • 22 mm = 0.022 m
  • 1,900 cm = 19 m