var BN=Import("zklBigNum");
BN(2).pow(64) * BN(2).pow(64)
340282366920938463463374607431768211456

BN(2).pow(128) : "%,d".fmt(_)
340,282,366,920,938,463,463,374,607,431,768,211,456

   //42!, also BN(42).factorial()
[2..42].reduce(fcn(p,n){p*n},BN(1)) : "%,d".fmt(_)
1,405,006,117,752,879,898,543,142,606,244,511,569,936,384,000,000,000