Then

Number of cutters
in set.
Number of
cutter.
8 - 7 = 1

Then

Number of teeth in
smallest wheel.
The number of the
cutter.
The number of the teeth
in largest wheel.
12 × 8 ÷ 300
12
8
300 ) 960 ( 0.32
900
600
600

Now add the 1 to the .32 and we have 1.32, which we must divide into the 96 first obtained.

Thus

1.32 ) 96.00 ( 72
924
360
264
96

Hence No. 8 cutter may be used for all wheels that have between 72 teeth and 300 teeth.

To find the range of wheels to be cut by the next cutter, which we will call No. 7, proceed again as before, but using 7 instead of 8 as the number of the cutter.