Question

How do you convert \[42\,cm\] to $mm$?

Answer 1

Hint: In the question, we have to find what number of millimetres corresponds to $42$ centimetres. We will use the unitary method to convert the units given to us. So, we will find the number of millimetres in one unit of centimetre and then multiply the equation by a suitable number so as to obtain the required answer.

Complete step-by-step solution:
The centimetres and millimetres are the units to measure the length of physical commodities or items. A centimetre is abbreviated as cm and millimetre is abbreviated as mm. A millimetre is a metric unit of length and it is used for measuring small lengths.
The given question requires us to convert the unit of length. We have to convert $42$ centimetres into millimetres.
We know that each centimetre of length consists of $10$ millimetres. So, $1\,cm = 10\,mm$.
Let the number of millimetres that correspond to $42$ centimetres be x.
Then, to convert $42$ centimetres into millimetres, we follow unitary method where we first find that how many units of millimetres correspond to a single unit of metre and then multiply both sides of the equation by a suitable number so as to get the desired conversion of $42$ centimetres.
So, $1$ centimetre $ = $ $10$ millimetres
Now, multiplying both the sides of the equation by $42$, we get,
Hence, $42$ centimetres $ = $ $420$ millimetres

Note: We have different units for solid quantity, liquid quantity and gaseous quantity. Every quantity has a measurement unit from the low quantity to the high quantity. While converting the unit of a quantity from one form to another form, we have a standard unitary conversion value. By multiplying or dividing we can convert the unit of the quantity. We have a different system of measurement of a quantity. One must take care of calculations while converting the units.