How many numbers PSAT question?

so 100,110, 120, 130, 140, 150, 160, 170, 180, 190 for for hundreds digits up to 9 so 10 numbers*9 dif. hundreds digits possible=90. 101-109 is 9 numbers. then hundreds digits one through 9 again. 9*9=81. I get 171 not sure what the other six are...