Question

How do you convert mm to cm, and kg to mg in metric system?

Answer 1

It's easy enough once you understand the prefixes. It is typically just multiplying and dividing by tens, thousands, millions etc.

Explanation:

In short: because there are 10 mm in each cm, the number will go down by a factor of 10 (thus 47.3 mm = 4.73 cm)

Similarly in 1 kg there are 1000 g hence 1000 000 mg so the number will increase by a factor of 1 million (2.7356 kg = 2735 600 mg)

Fundamentally, you need to understand SI prefixes here and then how to use standard form here and you're good to go. One final point, the c prefix as in cm is not formally part of the Système Internationale (SI) but is very common as a centimetre is such a useful scale for us humans.

Answer 2

Well `"milli"=10^-3`......

Explanation:

...and thus `1*mm-=1xx10^-3*m`

But `"centi"-=10^-2`....and thus `1*cm-=10^-2*m-=10*mm`

On the other hand `k-=10^3`, and `m-=10^-3` (remember that I am ALSO using the abbreviation `"m "-=" metre"`.)

And `1*kg-=1xx10^3*g`, and `1*mg-=1xx10^-3*g`.

And so `1*g-=1000*mg`, and `1*kg-=1000*g=10^6*mg`.

All I am doing is using the multipliers.......(hopefully appropriately)

`"micro"-=10^-6`, `"milli"-=10^-3`, `"centi"-=10^-2`, `"deci"-=10^-1`, `"kilo"-=10^3`.

One usage that is quite common in the UK is the use of `dm^3` for volume, in preference to `"litres"`. Now `1*dm^3-=1*L`, but `10^3*L=1*m^3`, and .............`1*dm^3-=(1xx10^-1*m)^3=10^-3*m^3=1*L` as required.

So how do you remember them? Keep practising, and note your mistakes. We all make mistakes.