1! = 1x1 = 1
2! = 2x1 = 2
3! = 3x2x1 = 6
4! = 4x3x2x1 = 24

//echo -a $fact(6) - 720
//echo -a $fact(5) - 120
//echo -a $fact(10) - 3628800

fact return $calc($left($regsubex($str(*,$1),/(?=\*)/g,\n),-1))

fact return $calc($regsubex($regsubex($str(*,$1),/./g,\n),/(?<=\d(?=\d))/g,*))

kare if $1 && $2 { var %k $calc($+($1,*,$1)) + $calc($+($2,*,$2)) | echo -a  $sqrt(%k) }

/kare 3 4 - 5
/kare 5 12 - 13

alias comb { if $regex($1,/\d+/) && $1 >= $2 { var %' $1,%! $2,%/ $calc($1 - $2),%\ 1,%. 1,%* 1 | while (%') { %. = $calc(%' * %.) |  dec %' } | while (%!) { %* = $calc(%! * %*) | dec %! } | while (%/) { %\ = $calc(%/ * %\) | dec %/ } | return $calc(%. / $calc(%* * %\)) } }

//echo > $comb(6,2) - 15
//echo > $comb(120,5) - 190578024
//echo > $comb(8,3) - 56

alias comb { return $calc($right($regsubex($str(*,$1),/(\*)/g,$+(\t,\n)),-1)/$calc($right($regsubex($str(*,$2),/(\*)/g,$+(\t,\n)),-1)*$right($regsubex($str(*,$calc($1 - $2)),/(\*)/g,$+(\t,\n)),-1)))  }

//echo -a $comb(4,2) - 6