.  We always round up to 
the next higher whole number, which is 8.  So we'll have 8 bars.  

We start at the bottom, the "x-axis" and build up.

The first bar will start at 0.5 less than the lowest value,
59-0.5=58.5.  

We add 5, getting 63.5, and mark that at the end of
the first bar, which will also be the beginning of the second bar.

Then we add 5 to 63.5, getting 68.5. Then we continue adding 5 until
we reach the 7th bar at the end of the histogram's horizontal axis. 

Now we start stacking the numbers up into into whichever of the 8 
categories they belong in.  

We start by stacking the first number in the list, 81, in the 5th bar 
from the left because it's between 78.5 and 83.5.  Then we stack the 
next number 70 on the 3rd bar becauser it's between 68.5 and 73.5. 
Then 73 goes on top of the 70 because it's also between 68.5 and 73.5,
then 89 goes on the next to the last bar because it's between 88.5 and
93.5, and so on and so forth.  We end up with this:
             ____
            | 77 |
            | 75 |     ____
        ____| 73 |    | 82 }
       | 67 | 77 |    | 82 |     ____         
   ____| 65 | 73 |____| 80 |____| 91 |____     
  | 59 | 68 | 70 | 79 | 81 | 88 | 89 | 94 |
  -----------------------------------------
58.5 63.5 68.5 73.5 78.5 83.5 88.5 93.5 98.5

Then we erase all the numbers we-ve stacked up
and just leave the bars:

             ____
            |    |
            |    |     ____
        ____|    |    |    }
       |    |    |    |    |     ____         
   ____|    |    |____|    |____|    |____     
  |    |    |    |    |    |    |    |    |
  -----------------------------------------
58.5 63.5 68.5 73.5 78.5 83.5 88.5 93.5 98.5

Or you teacher might not care if you leave the
numbers in there.  But you were probably told
just to count the number of numbers that go in
each bar and make the bars that high and not 
stack the numbers up.  But I think it's easier
to stack the numbers up.  You end up with the
same histogram either way.

Edwin