280 (number)

In today's world, 280 (number) has become a topic of great relevance and debate. Its impact covers various areas of society, from politics to popular culture. As time progresses, 280 (number) continues to be a topic of interest and analysis for experts and the general public. In this article, we will explore different aspects related to 280 (number), from its origins to its influence on everyday life. In addition, we will examine the different perspectives and opinions around 280 (number), with the aim of offering a comprehensive and complete view on this topic of global importance.

This article covers the number 280. For the year, see 280.

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Natural number

← 279 280 281 →
← 200 210 220 230 240 250 260 270 280 290 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred eighty
Ordinal	280th (two hundred eightieth)
Factorization	23 × 5 × 7
Greek numeral	ΣΠ´
Roman numeral	CCLXXX
Binary	1000110002
Ternary	1011013
Senary	11446
Octal	4308
Duodecimal	1B412
Hexadecimal	11816

280 (two hundred eighty) is the natural number after 279 and before 281.

In mathematics

The denominator of the eighth harmonic number, 280 is an octagonal number. 280 is the smallest octagonal number that is a half of another octagonal number.

There are 280 plane trees with ten nodes. As a consequence of this, 18 people around a round table can shake hands with each other in non-crossing ways, in 280 different ways (this includes rotations). ^{[disputed – discuss]}

Integers from 281 to 289

281

Main article: 281 (number)

282

Main article: 282 (number)

283

Main article: 283 (number)

284

Main article: 284 (number)

285

Main article: 285 (number)

286

Main article: 286 (number)

287

Main article: 287 (number)

288

Main article: 288 (number)

289

Main article: 289 (number)

References

1. ^ "Sloane's A002805 : Denominators of harmonic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.
2. ^ "Sloane's A000567 : Octagonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.