280 (number)

From HandWiki
Short description: Natural number

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

In mathematics

The denominator of the eighth harmonic number,[1] 280 is an octagonal number.[2] 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 ]

Integers from 281 to 289

281

Main page: 281 (number)

282

Main page: 282 (number)

283

Main page: 283 (number)

284

Main page: 284 (number)

285

Main page: 285 (number)

286

Main page: 286 (number)

287

Main page: 287 (number)

288

Main page: 288 (number)

289

Main page: 289 (number)

References