there are 28 stations between kolkatta and chennai . how many second class tickets have to be printed , so that a passenger can travel from any station to any other station ?
the total number of stations = 30 from 30 stations we have to choose any two stations and the direction of travel ( i . e . , kolkatta to chennai is different from chennai to kolkatta ) in 30 p 2 ways . 30 p 2 = 30 * 29 = 870 answer : a
multiply(multiply(const_3, const_10), 28)