For the simple question here is the simple answer:
as we know 1kg = 1000 grams
Formular for easy getting grams rate from per kg is looks like:
So g grams is g/1000 kg and the price will be g/1000 * r (rupees/kg)
or
rupees/kg= g*r/1000
For example to calculate the rate of 100 grams from per kg.
Let say we have some wheat item whose rate is 1 kg = 20 rupees and we have to calculate the rate for 100 grams wheat?100/1000 * 20 = 2 rupees
or100 * 20/1000 = 2 rupees
Hope this solves our understanings.
Happy learning!