if each year the population of the country grows by 40 % , how many years will elapse before the population of the country doubles ?
"till year 2000 , population is 100 . year 2001 : population becomes 140 . . . . . . . . . . . . . 1 year elapsed year 2002 : population becomes 196 . . . . . . . . . . . . . 2 year elapsed year 2003 : population > 200 . . . . . . . . . . . . . . . . . . 3 year elapsed answer : a"
add(const_4, const_4)