How many positive integers less than 1000 have at least one digit of 0 and at least one digit of 1?
10 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 120 , 130 , 140 , 150 , 160 , 170 , 180 , 190 , 201 , 210 , 301 , 310 , 401 , 410 , 501 , 510 , 601 , 610 , 701 , 710 , 801 , 810 , 901 , 910 , 1000 , >>Total = 37 such numbers
+118687 How many positive integers less than 1000 have at least one digit of 0 and at least one digit of 1?
So the digits will be
10 one of these
or
10* 10 of these
or
1*0 10 of these
take away one because you added 100 twice
* 10 where the * is between 2 and 9 inclusive . 8 of these
*01 where the * is between 2 and 9 inclusive . 8 of these
now add them up.
Guests way of just listing them was easier.
