What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
1
14
20
21

• 20%
  
  Explanation: 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 = 14 x 100 % = 20%.
  
• 12 years agoHelpfull: Yes(12) No(3)