Citizen E610 Instruction Manual page 95

[Calculation of driving distance]
Q : Supposing that the speed is 60km/hour, what distance will a vehicle travel
in 1 hour and 20 minutes ?
A : Align 60 of the outer scale with the SPEED INDEX "  " of the inner scale.
Result: 80km corresponding to 1:20 of the inner scale can be figured out.
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