Erwinia wrote in message <01bdcdd7$67fdf040$977d74cb at zrqzllmh>...
>>Can anyone explain to me what this unit is all about and how is it
>to any of the SI system we are using. I always have difficulty picturing
>quantity of the international unit.
Depends what you're measuring. Each material for which an international unit
is used presumably has an agreed reference standard which has a defined
number of units. What material are you interested in?