15 (number)

15 (fifteen) is the natural number following 14 and preceding 16.15 is: Furthermore, The Hanbali Sunni madhab states that the age of fifteen of a solar or lunar calendar is when one's taklif (obligation or responsibility) begins and is the stage whereby one has his deeds recorded.

[10]

M = 15
The 15 perfect matchings of K 6
15 as the difference of two positive squares (in orange).
Seashells from the mollusk Donax variabilis have 15 coloring pattern phenotypes .