If you are doing this exercise as a make-up or as homework, you can do it without a box of actual bolts.  Simply print out this page and use the bolt picture instead!  You can measure right off the picture.  The picture below shows all 15 bolts--you just won't have three or four of each.  The tops of some of the bolts are shown, and bolts that have a terminal groove that might not be readily visible are marked with an asterisk (*).
Back to the exercise!