Add BigInteger::remainder() method

This allows to return the remainder of the division only.

src/BigInteger.php

@@ -331,6 +331,22 @@ public function divideAndRemainder($that)
         return [$quotient, $remainder];
     }
 
+    /**
+     * Returns the remainder of the division of this number and the given one.
+     *
+     * @param BigInteger|int|string $that
+     *
+     * @return BigInteger
+     */
+    public function remainder($that)
+    {
+        $that = BigInteger::of($that);
+
+        list (, $remainder) = Calculator::get()->div($this->value, $that->value);
+
+        return new BigInteger($remainder);
+    }
+
     /**
      * Returns this number exponentiated.
      *

tests/BigIntegerTest.php

@@ -1104,6 +1104,21 @@ public function testDivideAndRemainderByZeroThrowsException()
         BigInteger::of(1)->divideAndRemainder(0);
     }
 
+    /**
+     * @dataProvider providerDivideAndRemainder
+     *
+     * @param string $dividend  The dividend.
+     * @param string $divisor   The divisor.
+     * @param string $quotient  The expected quotient (ignore for this test).
+     * @param string $remainder The expected remainder.
+     */
+    public function testRemainder($dividend, $divisor, $quotient, $remainder)
+    {
+        list (, $r) = BigInteger::of($dividend)->divideAndRemainder($divisor);
+
+        $this->assertSame($remainder, (string) $r);
+    }
+
     /**
      * @dataProvider providerPower
      *