I would like to formulate the classification with equal interval method.
I know how to formulate the interval:
$$ \frac{(Highest\;Value - Lowest\;Value)}{Number\;of\;Classes}=Interval\;Value $$
But how to assign a value to its class?
For example:
Value is 75 and Interval is 20.
$$
\frac{75}{20} = 3.5
$$
The class of value 75 is 3.
But I don't know how to formulize the whole number part of decimal number?
$$ \frac{Value}{Interval} = 3.5 ?? $$