What percentage of numbers from 1 to 70 have squares that end in the digit 1? 


(a) 
1 
(b) 
14 
(c) 
20 
(d) 
21 
What percentage of numbers from 1 to 70 have squares that end in the digit 1? 


(a) 
1 
(b) 
14 
(c) 
20 
(d) 
21 
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 numbers = 14.
Required percentage =