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4.2.4 Modular Integers
Let A and B be integers. The expression A%B has type ZMOD and represents the class of A modulo B. The integer B should be greater than 0 and less then 32767 = 215 - 1.

When a modular integer is evaluated by CoCoA, it is reduced to a canonical form A%B with -B/2 < A <= B/2.

Two modular integers of the form A%C and B%C are said to be compatible, and the usual arithmetical operations are applicable.

Example 
  3%7;
3 % 7
-------------------------------
  4%7;
-3 % 7
-------------------------------
  2%5 + 4%5;
1 % 5
-------------------------------
  Type(3%11);
ZMOD
-------------------------------
  3%11 = 14%11;
TRUE
-------------------------------
  3%11 * 3;
-2 % 11
-------------------------------
  3%11 = 3;  -- better and error than an unexpected answer!
ERROR: Cannot cast INT to ZMOD
CONTEXT:  ZPMK(3, 11) = 3
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Use the functions Div and Mod for quotients and remainders.