19°23′×4
=(19°+23′)×4
=19°×4+23′×4
=76°+92′
=76°+60′+32′
=76°+1°+32′
=77°32′
56°÷6
=(54°+2°)×1/6
=(54°+2×60′)×1/6
=(54°+120′)×1/6
=54°×1/6+120′×1/6
=9°+20′
=9°20′