540

[Math.]  Sum (in degrees) of all internal angles of a 5-side polygon.

 

[World]  The ISO-3166 country code for New Caledonia.

 

541

[Math.]  The 100th prime number.

 

[Sport] One of soccer’s possible lineup tactics formations: 5-4-1 (5 defenders, 4 midfielders and 1 forward). A slightly modified defenders line makes: 1-4-4-1 (1 sweeper), or 4-1-4-1 (1 stopper).

 

542…

 

543

[Math.]  Square and cube of number 543 use different digits: 5432 = 294,849 and 5433 = 160,103,007.

 

544

[Zip]  The only 2 U.S. Postal Zip Codes starting with 00: Holtsville, New York 00501 and 00544. Coincidentally, the only 2 U.S. Postal Zip Codes starting with 055 are: Andover, Vermont 05501 and 05544.

 

545

[Math.]  545 = 27+35+53+72 = 44+63+82+91.

 

 

544 & 545

[Math.]  (454+545 = 999 = 434+565)

4542 = 206,116 & 206+116 = 322

5452 = 297,025 & 297+025 = 322

and

4342 = 188,356 & 188+356 = 544

5652 = 319,225 & 319+225 = 544.

 

546

[Math.]  Sum 273+546 = 819 is one of only 4 cases that the equality: n+2n = 3n use each of 9 digits 1-9 once: n = 192, 219, 273 and 327.

 

548

[World]  The ISO-3166 country code for Vanuatu (was New Hebrides).

 

549...

 

540-549

[Library]  Numbers 500-599 are the first 3 digits in Dewey Decimal Classification System call numbers for library books in Pure Sciences (Mathematics, Astronomy and Chemistry…). Numbers 540-549 are for books in Chemistry and Mineralogy.