215 (number) - Alchetron, The Free Social Encyclopedia

215 216 → Factorization 5 × 43 Roman numeral CCXV		Cardinal two hundred fifteen Divisors 5, 43
Ordinal 215th(two hundred and fifteenth)

215 (two hundred [and] fifteen) is the natural number following 214 and preceding 216.

In mathematics

215 = ( 3 ! ) 3 − 1

215 is the second smallest integer (after 5) such that n 2 − 17 is twice a square: 215 2 − 17 = 2 × 152 2 .

There are 215 sequences of four integers, counting re-arrangements as distinct, such that the sum of their reciprocals is 1. These are

24 arrangements of (2,3,7,42), (2,3,8,24), (2,3,9,18), (2,3,10,15), (2,4,5,20) and (2,4,6,12).

12 arrangements of (3,3,4,12), (3,4,4,6), (2,3,12,12), (2,4,8,8) and (2,5,5,10).

6 arrangements of (3,3,6,6).

4 arrangements of (2,6,6,6).

1 arrangement of (4,4,4,4).

E215 is the E number of Sodium ethyl para-hydroxybenzoate.

215 is also:

The Dewey Decimal Classification for Science and religion.

The year AD 215 or 215 BC

215 is often used as slang for marijuana, from California Proposition 215, legalizing it for medical use.

The first area code of metropolitan Philadelphia, Pennsylvania

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