Your marlin 1893 was made in 1899.
the only rifle produced in cal 32-40 was the model 1893,either carbine or rifle,please check the model number again.
I would try the marlin firearms web site for a answer to your question.PLese be sure which model marlin you have.
3240
3240
3240 = 23 x 34 x 5
Answer: 3240 " = 90 yards.
The GCF is 72.
12 divided aided by 3240 = 0.003703703703703704
The answer depends on 3240 WHAT: seconds, days, years?
3240 = 23 x 34 x 51
The LCM is 3240.
Impossible to answer without knowing who made it and a detailed description of the entire weapon.