एकाकिना तपो द्वाभ्यां पठनं गायनं त्रिभिः।
चतुर्भिर्गमनं क्षेत्रं पञ्चभिर्बहुभी रणः॥
Penance is done alone, study by two, singing by three, travel by four, and war with many. Activities scale with participants.