900

[Calendar]  The last year of the 9th century.

 

[Math.]  A square number: 900 = 302.

 

[Math.]  Sum (in degrees) of all internal angles of a 7-side polygon.

 

[Phone]  An NANPA/U.S. telephone area code for the toll-call (cost-per-call) telephone number or value added information services. (NANPA: North American Numbering Plan Administration).

 

901

[Calendar]  The first year of the 10th century.

 

[Math.]

 1×8+1 = 9

12×8+2 = 98

123×8+3 = 987

1234×8+4 = 9876

12,345×8+5 = 98,765

123,456×8+6 = 987,654

1,234,567×8+7 = 9,876,543

12,345,678×8+8 = 98,765,432

123,456,789×8+9 = 987,654,321

1,234,567,890×8+90 = 9,876,543,210

      (start of a new cycle)

12,345,678,901×8+901 = 98,765,432,109

123,456,789,012×8+9,002 = 987,654,321,098

1,234,567,890,123×8+90,003 = 9,876,543,210,987

12,345,678,901,234×8+900,004 = 98,765,432,109,876

123,456,789,012,345×8+9,000,005 = 987,654,321,098,765

1,234,567,890,123,456×8+90,000,006 = 9,876,543,210,987,654

12,345,678,901,234,567×8+900,000,007 = 98,765,432,109,876,543

123,456,789,012,345,678×8+9,000,000,008 = 987,654,321,098,765,432

1,234,567,890,123,456,789×8+90000000009 = 9,876,543,210,987,654,321

12,345,678,901,234,567,890×8+ 900000000090 = 98,765,432,109,876,543,210

...   (end of cycle)...

  

902...

 

903     

[Math.]  A triangular number (sum of all integers from 1 to 42): 903 = 1+2+…+41+42.

 

904...

 

905...

 

906...

 

907

[Math.]  A sequence of prime numbers: 9999907, 999907, 99907, 9907, 907 and 07.

  

[Measure]  1 short ton = 20 hundredweights = 2,000 lb (pounds) = 907.1847 kg (kilograms). 1 long ton (or gross ton) = 20 long (gross) hundredweights = 2,240 lb (pounds) = 1016.0469 kg (kilograms).

 

[Phone]  The only telephone area code for the state of Alaska, U.S.

 

908

[Math.]  908 = 67+179+283+379 may be the smallest sum of 4 prime numbers of the property that sum of any three prime numbers is a square number.

 

909

[Math.]  9092 = 826,281 = (826+2+81)2.

 

900-909      

[Library]  Numbers 900-999 are the first 3 digits in Dewey Decimal Classification System call numbers for library books in History and Geography. Numbers 900-909 are for general & dictionary works.