We can convert each of the decimals, to numbers by moving the decimal point:
So, Japan=12.718*10^7=12718*10^4=127,180,000
Brazil: 2.0*10^8=2*10^8=200,000,000 ( Most Populated)
Germany: 80.619*10^6=80619*10^3=80, 619,000
United Kingdom: 63,708,000
Nigeria: 0.00173615*10^11=173615*10^3=173, 615, 000
Bangladesh: 15, 251*10^4=152, 510, 000
So,
Brazil
Nigeria
Japan
Bangladesh
Germany
United Kingdom