Explain how to find out the number of classes required for a frequencydistribution with the help of range?

Follow the given link and scroll down to the topic 'Relative frequency distribution' and 'Frequency distribution with unequal class'.

https://www.meritnation.com/cbse/class11-commerce/studymaterial/economics/statistics-for-economics/organisation-of-data/443_2495_6425#slide1_Frequency Distribution and its Types