need explanation on simple time calculation

In front of me is Walkenbachs excel bible 2003. Chapter 10 page 220. Figure
10-10.

There are two cells
B2 giving a distance (the example gives 1.50 miles).
C2 giving a time needed to run that distance (the example gives 00:18:45).

Now in D2 he makes the calculation =B2/(C2*24)
This gives the speed in mph.

The part I find difficult to understand is the "24"....

My normal feeling lets me divide B2 by C2 to give me a distance per
'minute'. The result of this, times 60, would give me mph.
Now I think I know this 'minute' I mention is wrong. But I find it difficult
to understand why to multiply by 24. Can somebody explain it more
understandable?

G.

The way that Excel stores times is as fractions of a 24-hour day. So
the time 12:00:00 would be stored internally as 0.5, and 6:00:00 as
0.25. So, if you divide miles directly by the recorded time, you would
have miles per day - if you want miles/hour you must also do a further
division by 24, and if you want miles per minute then you would divide
by a further 60.

Let's say a car does 60 miles/hour. Then in one minute it will only
travel 1 mile. In one day (assuming no stops for petrol etc) it could
travel 1440 miles (24 x 60)

Hope this helps.

Pete