Question

Fill in the blanks
12 cm 8 mm = ______ mm.

Answer 1

Hint: Convert the unit of centimetres into millimetres. Use the operations of multiplication and addition in order to reach the final solution. Also, we are aware of the fact that one centimetre is equal to ten millimetres.

Complete step-by-step answer:
We all know about the universal fact in the field of measurement that one centimetre is equal to ten millimetres.
It can be written in the form
$ 1{\rm{ cm = 10 mm}} $ .
The question asks the value of 12 cm 8 mm in the form of millimetres.
In short, 12 cm is to be converted into mm.
1 cm = 10 mm, therefore
$ 12{\rm{ cm = 12 }} \times {\rm{ }}\left( {{\rm{1 cm}}} \right) $
We know that 1 cm = 10 mm.
Now, we can substitute the value of 1 cm in the equation
 $ \Rightarrow 12{\rm{ cm = 12 }} \times {\rm{ }}\left( {{\rm{1 cm}}} \right) $ .
After substituting the value of 1 cm, we get $ 12{\rm{ cm = 12 }} \times {\rm{ }}\left( {{\rm{10 mm}}} \right) $ which is equal to 120 mm.
So, 12 cm in the form of mm is equal to 120 mm.
Therefore,
 $
\Rightarrow 12{\rm{ cm 8 cm = }}\left( {{\rm{120 + 8}}} \right){\rm{ mm}}\\
{\rm{ = 128 mm}}
 $

Therefore, $ 12{\rm{ cm 8 cm = 128 mm}} $.

Additional Information:
Any randomly chosen reference which is accepted widely for measuring the length is termed as unit of length. The U.S. customary units as well as the metric units are widely used in many countries. Also, British introduced imperial units which are also in use in some of the countries across the globe.
In India, the standard system for measurement is the SI system. The SI unit for length is metres. It is a well established fact that, $ {\rm{1 m = 100 cm, 1 cm = 10 mm, 1 m = 1000 mm}} $ .
Centimetres and millimetres are the unit of length. In addition to this, metres, feet, inches, etc are also the unit of measurement of lengths.

Note: Keep in mind that $ 1{\rm{ cm = 10 mm}} $ and $ 1{\rm{ mm }} \ne {\rm{ 10 cm}} $ . Students might get confused and might use the wrong value instead of the right value i.e. $ 1{\rm{ cm = 10 mm}} $ . Appropriate operations such as addition, subtraction, multiplication or division are to be done in order to find the solutions in this type of question.