For a development heading, the blasting parameters are

Cross-section: 6.0 m × 5.0 m

Total number of holes: 72

Number of trimmer holes: 30

Depth of each hole: 3.5 m

Charge per hole (except trimmers): 3.5 kg

Charge per trimmer hole: 1.8 kg

Pull per round: 90% of hole depth

The powder factor for the development round in m³/kg is ______ (round off to 2 decimal places).