How many digits are required to number a book containing 250 pages?  Options.
A) 756  B) 642  C) 492  D) 372  E) 250

Rationale: "9 pages from 1 to 9 will require 9 digits . 90 pages from 10 to 99 will require 90 * 2 = 180 digits . 250 - ( 90 + 9 ) = 151 pages will require 151 * 3 = 453 digits . the total number of digits is 9 + 180 + 453 = 642 . the answer is b ."
Answer: B