What percentage of numbers from 1 to 20 have squares that end in the digit 9?
Choose the correct option:  A) 1  B) 14  C) 20  D) 21  E) 22
Clearly, the numbers which have 1 or 9 in the unit's digit, have squares that end in the digit 1. Such numbers from 1 to 18 are 3,7,13,17.   Number of such numbers = 4.   Required percentage = (4/18 * 100) = 22%   ANSW22R:22
<result>E</result>
What percentage of numbers from 1 to 20 have squares that end in the digit 9?