Question

What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?A1b14c20d21?

Answer 1

Answer:    

20%

Step-by-step explanation:

Numbers having 1 in the unit's digit are 1,11,21,31,41,51,61     =  7 numbers

Numbers having 9 in the unit's digit are 9,19,29,39,49,59,69      =  7 numbers

So there are (7+7)=14 numbers having 1 or 9 in the unit's digit.

Therefore percentage of numbers from 1 to 70 having 1 or 9 in the unit's digit is given by   =  (14/70)*100%

                            =   (2/10)*100%

                            =    20%