What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?  Choose the correct choice:
A) 12 %	B) 16 %	C) 18 %	D) 20 %	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 70 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.   Number of such number =14   Required % = (14/70)x100 % =20 %   answer : 20 %
<result>D</result>
What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?