Add ceiling division operation to the Math.sol library (#2681)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/utils/math/Math.sol

@@ -28,4 +28,15 @@ library Math {
         // (a + b) / 2 can overflow, so we distribute.
         return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
     }
+
+    /**
+     * @dev Returns the ceiling of the division of two numbers.
+     *
+     * This differs from standard division with `/` in that it rounds up instead
+     * of rounding down.
+     */
+    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
+        // (a + b - 1) / b can overflow on addition, so we distribute.
+        return a / b + (a % b == 0 ? 0 : 1);
+    }
 }