What is the collective name for the digits before and after decimal point? What is the collective name for the digits before and after decimal point?
The part before the decimal point, the whole number $120$ in your example, is often referred to as the Characteristic and can be seen here https://mathworld.wolfram.com/Characteristic.html. The part after the decimal point, the fractional part $590$ in your example, can be referred to as the Mantissa. More information on this can be found here https://mathworld.wolfram.com/Mantissa.html.

Hope this helps!
It's called the Number of Significant Figures.
https://en.wikipedia.org/wiki/Significant_figures