Question

How far can a bike rider traveling at 5.2 m/s go in 15 seconds

Answer 1

If he's traveling at 5.2 m/s, then he covers
5.2 meters in the 1st second
5.2 meters in the 2nd second
5.2 meters in the 3rd second
5.2 meters in the 4th second
.
.
.
.
5.2 meters in the 14th second, and
5.2 meters in the 15th second.

He covers 5.2 meters 15 times in 15 seconds.
To find the total distance, you could write down 5.2 meters
15 times and add them all up.  Or you could use the newly-
discovered, labor-saving process called 'multiplication' to do
the same thing.  With multiplication, it can be done in one line:

        (5.2 m/s) x (15 sec)  =  78 meters .