+1632 How many three-digit whole numbers have at least one 7 or at least one 9 as digits?
No overcounting, so for example, 179 or 197 is counted ONCE and not TWICE.
Thanks! 
+678 107, 109, 117, 119, 127, 129, 137, 139, 147, 149, 157, 159, 167, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 187, 189, 190, 191, 192, 192, 193, 194, 195, 196, 197, 198, 199 (37)
207, ... , 299 (37)
...
700, ... , 799 (100)
...
900, ... , 999 (100)
37 * 7 = 259
259 + 100 + 100 = 459
777 and 999 (- 2) and 171/191, 272/292, 373/393, 474/494, 575/595, 676/696, 797, 878/898, 979 (- 16)
(- 16) - (- 2) = (- 18)
459 - 18 = 441
So there are (457 - 18 =) 441 numbers that at least have one 7 or one 9 as digits.
Correct me if I am wrong. (probably wrong)
