The height of a person is $$1\ m\ 65\ cm$$. His height in millimetres is _________.
Correct option is A. $$1650\ mm$$
We know that,
$$1\ m=1000\ mm$$ and $$1\ cm =10 \ mm$$
$$\therefore 1\ m\ 65\ cm= (1000\ mm)+(65\times10\ mm)\\=(1000+650)\ mm=1650\ mm$$
Hence, the height of the person in millimetre is $$1650\ mm.$$