multiply a factor by number of rows

Is it possible to multiply a factor by the number of rows in a table? 

For example say that every time a robot does a job, it comes up as a row in the table (one job equals one row), meaning that the number of rows will continue to grow. 
Every time a job is done by the robot it saves 60 minutes of company time. 

Is it possible to make a syntax that multiplies: 60 x "number of rows", and so that the result always shows the minutes saved all in all?