MathDB

How many of the numbers,

100,101,\ldots,999

, have three different digits in increasing order or in decreasing order?

\text{(A)} \ 120 \qquad \text{(B)} \ 168 \qquad \text{(C)} \ 204 \qquad \text{(D)} \ 216 \qquad \text{(E)} \ 240

Problem Statement