The population of a country increased by an average of 2% per year from 2000 to 2003. If the population of this country was 2 000 000 on December 31, 2003, then the population of this country on January 1, 2000, to the nearest thousand would have been

Population in succeed year is 1.02 time previous year ( 2% is 2/100 i.e 1+0.02)
So population in 2003 will be 1.02(Population in 2002) = 1.02 ( 1.02(Poupluation in 2001)) =1.02*1.02*1.02(Population in 2001)
So population in 2001 is poulation in 2003/ (1.02) ​³
= 2000000/(1.02)​³​