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BigNum

/big'nuhm/

[orig. from MIT MacLISP]

n. 1. [techspeak] A multiple-precision computer representation for very large integers. More generally, any very large number. "Have you ever looked at the United States Budget? There's bignums for you!"

2. [Stanford] In backgammon, large numbers on the dice are called 'bignums', especially a roll of double fives or double sixes (compare moby, sense 4).

See also El Camino Bignum.

Sense 1 may require some explanation. Most computer languages provide a kind of data called 'integer', but such computer integers are usually very limited in size; usually they must be smaller than than 231 (2,147,483,648) or (on a losing bitty box) 215 (32,768). If you want to work with numbers larger than that, you have to use floating-point numbers, which are usually accurate to only six or seven decimal places. Computer languages that provide bignums can perform exact calculations on very large numbers, such as 1000! (the factorial of 1000, which is 1000 times 999 times 998 times ... times 2 times 1). For example, this value for 1000! was computed by the MacLISP system using bignums:

402387260077093773543702433923003985719 374864210714632543799910429938512398629 020592044208486969404800479988610197196 058631666872994808558901323829669944590 997424504087073759918823627727188732519 779505950995276120874975462497043601418 278094646496291056393887437886487337119 181045825783647849977012476632889835955 735432513185323958463075557409114262417 474349347553428646576611667797396668820 291207379143853719588249808126867838374 559731746136085379534524221586593201928 090878297308431392844403281231558611036 976801357304216168747609675871348312025 478589320767169132448426236131412508780 208000261683151027341827977704784635868 170164365024153691398281264810213092761 244896359928705114964975419909342221566 832572080821333186116811553615836546984 046708975602900950537616475847728421889 679646244945160765353408198901385442487 984959953319101723355556602139450399736 280750137837615307127761926849034352625 200015888535147331611702103968175921510 907788019393178114194545257223865541461 062892187960223838971476088506276862967 146674697562911234082439208160153780889 893964518263243671616762179168909779911 903754031274622289988005195444414282012 187361745992642956581746628302955570299 024324153181617210465832036786906117260 158783520751516284225540265170483304226 143974286933061690897968482590125458327 168226458066526769958652682272807075781 391858178889652208164348344825993266043 367660176999612831860788386150279465955 131156552036093988180612138558600301435 694527224206344631797460594682573103790 084024432438465657245014402821885252470 935190620929023136493273497565513958720 559654228749774011413346962715422845862 377387538230483865688976461927383814900 140767310446640259899490222221765904339 901886018566526485061799702356193897017 860040811889729918311021171229845901641 921068884387121855646124960798722908519 296819372388642614839657382291123125024 186649353143970137428531926649875337218 940694281434118520158014123344828015051 399694290153483077644569099073152433278 288269864602789864321139083506217095002 597389863554277196742822248757586765752 344220207573630569498825087968928162753 848863396909959826280956121450994871701 244516461260379029309120889086942028510 640182154399457156805941872748998094254 742173582401063677404595741785160829230 135358081840096996372524230560855903700 624271243416909004153690105933983835777 939410970027753472000000000000000000000 000000000000000000000000000000000000000 000000000000000000000000000000000000000 000000000000000000000000000000000000000 000000000000000000000000000000000000000 000000000000000000000000000000000000000 00000000000000000000000000000000