Representation numerals

ιεʹ

١٥

XV

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十五

טו

Numeral systems

Binary: 1111

Septimal (base 7): 21

Octal: 17

Hexadecimal: f

Base 24: F

Sums & differences

Difference of 2 squares: 15 = 8^{2} - 7^{2}

Characteristics

15 is a hexagonal number

15 is a palindromic number in binary system (1111)