What percentage of the numbers from 101 to 1000 have 9 in the unit's digit?

10%

Numbers from 101 to  200 with unit digit 9 = 109 , 119 , 129 , 139 , 149 , 159 , 169 , 179 , 189 , 199

So, From 101 to 200 = there are 10 such numbers

Similarly , from 201 to 1000  there are 10 × 8 = 80

So , Total numbers with 9 at unit digit = 10 + 80 = 90

Required percentage  =   \(\frac{90}{900}\) × 100

= 10%