Change value automatically with drop down list

Hi
I want to change values with drop down list. For example drop down list has two options one in centimeter and another in inch.
So if I have already entered values with one of the options (suppose 73 in inch) and when I want to see it in other option I just select it in drop list and the cell changes its value accordingly (185.42 in centimeter). Is that possible?

Originally Posted by oeldere

This is one of the solutions (see G3) (yellow cell).

Thanks a lot Oeldere. It almost solved my problem. Still want to know if is there any way to convert value in the "same cell" that works like a converter.
Whatever I enter in cell is converted to other value if I pick the other option from drop down list.

Oeldere your English is great. Thanks again.