Arrange the following length in their increasing magnitude:
1 meter, 1 centimetre, 1 kilometre, 1 millimetre.

Hint: According to the question we have to arrange the following length in their increasing magnitude. So, first of all we have to convert all the given lengths into the same units as all length are in metre, all length are in centimetre, all length are in kilometre and all lengths are in millimetre.
For example:
First of all we have to convert centimetre into meter with the help of the formula given below.

Formula used:
1 centimetre $ = \dfrac{1}{{100}}$metre \[\]
First of all we have to convert kilometers into meters with the help of the formula given below.
1 kilometre $ = {10^3}$metre \[\]
First of all we have to convert millimetre into meter with the help of the formula given below.
1 millimetre $ = {10^{ - 3}}$metre \[\]
Now, we have to compare all lengths in metre which is obtained by the examples explained just above and arrange into their increasing magnitude.

Complete answer:
Step 1: First of all we have to convert the centimetre into meters with the help of the formula which is mentioned in the solution hint.
1 centimetre $ = \dfrac{1}{{100}}$metre
1 centimetre $ = {10^{ - 2}}$metre \[\]
Step 2: Similarly, we have to convert kilometers into meters with the help of the formula which is mentioned in the solution hint.
1 kilometre $ = {10^3}$metre \[\]
Step 3: Similarly, we have to convert millimetre into meters with the help of the formula which is mentioned in the solution hint.
1 millimetre $ = {10^{ - 3}}$metre \[\]
Step4: Now, we have to compare all lengths in meters that are calculated above in all steps.
$ \Rightarrow {10^{ - 3}}$meter$ < {10^{ - 2}}$metre$ < 1$metre$ < {10^3}$metre

Hence, we have to arrange all given lengths into their increasing magnitude that is ${10^{ - 3}}$ meter$ < {10^{ - 2}}$metre$ < 1$metre$ < {10^3}$metre.

Note:
It is necessary that we have to convert all given dimensions into the same unit which is as in metre with the help of the formulas as mentioned in the solution hint to convert the given different dimension into metre.
To arrange the obtained dimensions in metre, we have to compare all of them so that we can align them in increasing order.