The function calculates the number of payment periods in an investment or loan.

The NPER function calculates the number of payment periods in an investment or loan. NPER is a function in microsoft excel from the category Financial Function. It  that can be used to get the number of payment periods for a loan, given the amount, the interest rate, and periodic payment amount.

Real GDP per capita is a measurement of the total economic output of a country divided by the number of people and adjusted for inflation. 

Explanation:

I'm not sure if this is what you were looking for but this is my answer.