How many integers between 7000 and 8000 that have distinct digits and increase from left to right ?  Pick one:
A) 30  B) 48  C) 60  D) 20  E) 100
Since the numbers must be distinct and increasing from left to right,   The only arrangements we could come-up with are:   745_ --&gt; 4   746_ --&gt; 3   747_ --&gt; 2   748_ --&gt; 1   756_ --&gt; 3   757_ --&gt; 2   758_ --&gt; 1   767_ --&gt; 2   768_ --&gt; 1   778_ --&gt; 1   Number of integers =20   20
<result>D</result>
How many integers between 7000 and 8000 that have distinct digits and increase from left to right ?