1/68 inch, presumably.
If you mean 68 then it is 68/1 but if you mean 6/8 then it is 3/4
68 = 68/1
68 into fraction = 68/1
68/1
six and four fifths, or thirty four fifths for top heavy fraction
In its simplest form it is 68 over 1.
68/1 6/8 = 3/4
one quarter inch written as a fraction is 1/4 inch.
34 1 caliber is an an inch. so if it is .68 of an inch, its radius half: 34
About 1/2 inch.
1/78 inch
1/1250th of an inch