#001 = 1
#002 = 2
#003 = 3
#004 = 4
#005 = 5
#006 = 6
#007 = 7
#008 = 8
#009 = 9
#00A = 10
#00B = 11
#00C = 12
#00D = 13
#00E = 14
#00F = 15

10進数で15だな

この手の基本は枚挙だ
式だけを覚えるな
手で数え上げろ