diff --git a/lib/function/probability/combinations.js b/lib/function/probability/combinations.js
index 912c95155..d00ce258d 100644
--- a/lib/function/probability/combinations.js
+++ b/lib/function/probability/combinations.js
@@ -34,6 +34,27 @@ module.exports = function (math) {
       }
       return Math.floor(math.factorial(n) / (math.factorial(k) * math.factorial(n-k)));
     }
+
+    var isPositiveInteger = function(x) {
+      if (!x.round().equals(x) || x.lt(0)) {
+        return false;
+      }
+      return true;
+    };
+
+    if (n instanceof BigNumber) {
+        // make sure k is a BigNumber as well
+        k = new BigNumber(k);
+        if (isPositiveInteger(n) && isPositiveInteger(k)) {
+          return math.floor(math.divide(math.factorial(n),
+                      math.multiply(math.factorial(k),
+                          math.factorial(math.subtract(n, k)))));
+        }
+        else {
+          throw new TypeError('Positive integer value expected in function permutations');
+        }
+    }
+
     throw new math.error.UnsupportedTypeError('combinations', n);
   };
 };
diff --git a/lib/function/probability/permutations.js b/lib/function/probability/permutations.js
index b4f67270e..c1b2a1552 100644
--- a/lib/function/probability/permutations.js
+++ b/lib/function/probability/permutations.js
@@ -59,11 +59,13 @@ module.exports = function (math) {
 
     if (n instanceof BigNumber) {
         if (k === undefined && isPositiveInteger(n))
-            return math.factorial(n);
+          return math.factorial(n);
         // make sure k is a BigNumber as well
         k = new BigNumber(k);
         if (isPositiveInteger(n) && isPositiveInteger(k)) {
-          return math.divide(math.factorial(n), math.factorial(math.subtract(n, k)));
+          return math.floor(math.divide(math.factorial(n),
+                      math.factorial(
+                          math.subtract(n, k))));
         }
         else {
           throw new TypeError('Positive integer value expected in function permutations');
diff --git a/test/function/probability/combinations.test.js b/test/function/probability/combinations.test.js
index ecd0fa1a1..395ec3c9c 100644
--- a/test/function/probability/combinations.test.js
+++ b/test/function/probability/combinations.test.js
@@ -11,6 +11,11 @@ describe('combinations', function() {
     assert.equal(combinations(63, 7), 553270671);
   });
 
+  it('should calculate the combinations of n items taken k at a time with BigNumbers', function() {
+      assert.deepEqual(combinations(math.bignumber(7), math.bignumber(5)), math.bignumber(21));
+      assert.deepEqual(combinations(math.bignumber(20), math.bignumber(15)), math.bignumber(15504));
+  });
+
   it('should not work with non-integer and negative input', function() {
       assert.throws(function() {combinations(0.5, 3)});
       assert.throws(function() {combinations(3, 5)});