The population of a town is 10000. It decreases annually at the rate of 20% p.a. What will be its population after 2 years?  Choices
A) 6400
B) 4500
C) 5120
D) 5230
E) 5366

Rationale: "10000 × 80 / 100 × 80 / 100 = 6400 answer : a"
Answer: A