a:
, n:
, q,r:. a = q
n+r 
|r| < |n| (r < 0 a < 0) (r > 0 a > 0) q = (a 
n) & r = (a rem n)a:, n:. a = (a n)n+(a rem n) & |a rem n| < |n| & ((a rem n) < 0 a < 0) & ((a rem n) > 0 a > 0)a,b:. |ab| = |a||b|a,b:, n:
. a
b nanb