*Ahem* You are quite wrong about it sir!
You are conflating GDP (Constant Dollars) with GDP (nominal, current USD) Per Capita.
GDP (nominal, current USD) can be calculated using a number of methods :
1. The expenditures approach
2. The factor income approach
3. Value add approach
However, GDP Per Capita is indeed calculated by dividing GDP by Population.
Don't believe me? Okay! Here is a simple experiment. Let us take country say Pakistan and see its GDP (nominal, current $) per capita for 2016, 2015, 2014 and compare it with the formula used here.
2016
GDP : $ 283.66 Billion (
http://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=PK)
Population : 193203476 (
http://data.worldbank.org/indicator/SP.POP.TOTL?locations=PK)
GDP Per Capita : $1468.193 (
http://data.worldbank.org/indicator/NY.GDP.PCAP.CD?locations=PK)
GDP divided by Population : 283660000000 / 193203476 = 1468.1930463818362
2015
GDP : $ 283.66 Billion (
http://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=PK)
Population : 189380513 (
http://data.worldbank.org/indicator/SP.POP.TOTL?locations=PK)
GDP Per Capita : $1431.245 (
http://data.worldbank.org/indicator/NY.GDP.PCAP.CD?locations=PK)
GDP divided by Population : 271050000000 / 189380513 =1431.2454629373615
2014
GDP : $ 244.361 Billion (
http://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=PK)
Population : 185546257 (
http://data.worldbank.org/indicator/SP.POP.TOTL?locations=PK)
GDP Per Capita : $1316.981 (
http://data.worldbank.org/indicator/NY.GDP.PCAP.CD?locations=PK)
GDP divided by Population : 244361000000 / 185546257 = 1316.9815654109368
So you can see GDP (nominal, USD) Per Capita can
indeed be calculated by dividing GDP (nominal, USD) by population. Hence in 2017, if the predicted GDP comes out to be 305 billion and population ( which will be officially declared by the end of July based on stats collected from 2017 census) comes out to be 210 million , Pakistani GDP (nominal, USD) Per Capita will indeed be $1452.380 and indeed Bangladeshi GDP (nominal, USD) per capita will cross Pakistani's figure.