Seventyfive

Seventy-five is the integer 75, the natural number following 74 and preceding 76. In numerals, it is written as 75 in decimal, LXXV in Roman numerals, 0b1001011 in binary, and 0x4B in hexadecimal. The common English name is seventy-five, often hyphenated; the concatenated form seventyfive is not standard.

The name combines "seventy" (seven tens) with "five." The word seventy comes from Old English seofontig and related Germanic forms; five derives from Old English fife.

In mathematics, 75 is an odd composite number with prime factorization 3 × 5^2. Its positive divisors are 1, 3, 5, 15, 25, and 75, giving it six divisors. It is a multiple of 3, 5, 15, 25, and 75. Euler's totient function φ(75) = 40. In base 10 its digits sum to 12.

In science and measurement, 75 is the atomic number of rhenium (Re), a rare transition metal used in high-temperature alloys and catalysts. The fraction 3/4 is equal to 0.75, and 75 percent represents three quarters.

In culture and everyday use, 75 appears in contexts such as percentages, anniversaries, or historical years (e.g., year 75 CE). When describing time, 75 minutes equals one hour and fifteen minutes.