9,900

[Math.]  Sum (in degrees) of all internal angles of a 57-side polygon.

 

9,901

[Math.]   (Sequence of  numbers (10n–99), n > 3).

99012 = 98029801 = (9802+98+01)2 = 99012.

99013 = 970593059701 = (9705+93+05+97+01)2 = 99012.

99014 = 9609841884099601 = (9609+84+18+84+09+96+01)2 = 99012.

 

9,901

[Math.] 

1,001 = 11×91

1,000,001 = 101×9901

1,000,000,001 = 1,001×999,001

1,000,000,000,001 = 10,001×99,990,001

1,000,000,000,000,001 = 100,001×9,999,900,001

  

[Math.]  Square numbers, which are concatenation of 2 consecutive numbers:

78102 = 60,996,100; 90792 = 82,428,241 and 99012 = 98,029,801.

 

9,907

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

 

9,909

[Math.]  (Sequence of numbers (10n–91), n > 2)

99092 = 98,188,281 =  (9818+8+2+81)2 = (9818+82+8+1)2 = 99092.

 

9,914

[Math.]   99142 = 98,287,396 = (9828–7–3+96)2.

 

9,918

[Math.]  99182 = 98,366,724 = (9836+6+72+4)2.

 

9,933

[Math.]  Two consecutive sums of consecutive numbers: (largest 4-digit)

441+442+…+462 = 463+464+…+483 = 9933.

 

9,941

[Math.]  A prime number.  A Mersenne exponent: 29941–1 is the 22nd Mersenne prime number.

 

9,944

[Library]  ISBN-9944 and ISBN-975 are the International Standard Book Number codes for books published in United Arab Emirates.

 

9,945

[Library]  ISBN-99934 and ISBN-9945 are the International Standard Book Number codes for books published in Dominican Republic.

 

[Math.]  (Sequence of numbers (10n–55), n > 3).

99452 = 98,903,025 and 9890+30+25 = 9945.

 

 9,946

[Library]  ISBN-9946 is the International Standard Book Number for books published in P.D.R. Korea.

 

9,947

[Library]  ISBN-9961 and ISBN-9947 are the International Standard Book Number codes for books published in Algeria.

 

9,948

[Library]  ISBN-9948 is the International Standard Book Number for books published in United Arab Emirates.

 

9,949

[Library]  ISBN-9949 and ISBN-9985 are the International Standard Book Number codes for books published in Estonia. Also, ISBN-5 for the former USSR.

 

 [Math.]  A prime number.

 

9,950-9,969 (separate page)

 

9,970-9,989 (separate page)

 

9,990-9,999 (separate page)