What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?	Choose the correct option:	A) 10%	B) 30%	C) 20%	D) 70%	E) 45%
D   20%   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 70 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.   Number of such number =14   Required percentage =(14x100/70) % = 20%.
<result>C</result>
What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?