500 (separate page)

501

[Calendar] The first year of the 6th century.

[Math.] Its odd powers end with 501. Its even powers end with 001.

[Phone]  International telephone dialing code for Belize.

[Sport]  One of the popular beginning scores to play down to exactly zero in a dartboard game tournament: 501, 301, 601, 801 and 1001…, which always end with 01. Higher scores are usually played by teams.

[Zip]  The smallest number for a U.S. Postal Zip Code: Holtsville, New York 00501. The only 2 U.S. Postal Zip Codes starting with 00: Holtsville, New York00501 and 00544. Coincidentally, the only 2 U.S. Postal Zip Codes starting with 055 are: Andover, Vermont 05501 and 05544.

502

[Measure]  1 rod = 502.92 cm (centimeters).

U.S. customary units for linear measures: 1 mile = 8 furlongs = 320 rods = 1,760 yards = 5,280 feet = 63,360 inches.

[Phone]  International telephone dialing code for Guatemala.

503

[Math.]    A prime number.

[Phone]  International telephone dialing code for El Salvador.

504

[Math.]

12×21 = 252 = 21×12

12×42 = 504 = 21×24          24×21 =    504 = 42×12

12×63 = 756 = 21×36          24×63 = 1,512 = 42×36

12×84 = 1,008 = 21×48       24×42 = 1,008 = 42×24

36×84 = 3,024 = 63×48       24×84 = 2,016 = 42×48.

[Phone]   International telephone dialing code for Honduras.

[World]   The ISO-3166 country code for Morocco.

505

[Math.]    A cube number which is sum of 3 cube numbers: 5053 = 593+1633+4993 = 128,787,625.

[Phone]   International telephone dialing code for Nicaragua.

506

[Math.]    A pyramidal number (sum of all squares of integers from 1 to 11):

506 = 12+22+32+42+52+62+72+82+92+102+112.

[Phone]  International telephone dialing code for Costa Rica.

507

[Phone]  International telephone dialing code for Panama.

508

[Phone]  International telephone dialing code for Saint-Pierre and Miquelon.

[World]   The ISO-3166 country code for Mozambique.

509

[Math.]  A prime number.

[Math.]  The 509 direct collaborators with Paul Erdös for mathematical papers, have “Erdös number 1”. The direct collaborators of these people of “Erdös number 1” have “Erdös number 2” and so on.

[Phone]  International telephone dialing code for Haiti.

500-509

[Library]  Numbers 400-499 are the first 3 digits in Dewey Decimal Classification System call numbers for library books in Pure Sciences (Mathematics, Astronomy and Chemistry…). Numbers 500-509 are for general & dictionary works.