diff --git a/docs/expressions/customization.md b/docs/expressions/customization.md
index 08af41ce0..8af9223f8 100644
--- a/docs/expressions/customization.md
+++ b/docs/expressions/customization.md
@@ -197,7 +197,8 @@ The functions `toTex` and `toString` accept an `options` argument to customise o
 ```js
 {
   parenthesis: 'keep',   // parenthesis option
-  handler: someHandler   // handler to change the output
+  handler: someHandler,   // handler to change the output
+  implicit: 'hide' // how to treat implicit multiplication
 }
 ```
 
@@ -325,3 +326,20 @@ var expression = math.parse('binomial(2,1)');
 var latex = expression.toTex({handler: customLaTeX});
 //latex now contains "\binom{2}{1}"
 ```
+
+### Implicit multiplication
+
+You can change the way that implicit multiplication is converted to a string or LaTeX. The two options are `hide`, to not show a multiplication operator for implicit multiplication and `show` to show it.
+
+Example:
+```js
+var node = math.parse('2a');
+
+node.toString(); //'2 a'
+node.toString({implicit: 'hide'}); //'2 a'
+node.toString({implicit: 'show'}); //'2 * a'
+
+node.toTex(); //'2~ a'
+node.toTex({implicit: 'hide'}); //'2~ a'
+node.toTex({implicit: 'show'}); //'2\\cdot a'
+```
diff --git a/examples/browser/pretty_printing_with_mathjax.html b/examples/browser/pretty_printing_with_mathjax.html
index 5a8d5019a..c59e0c0a9 100644
--- a/examples/browser/pretty_printing_with_mathjax.html
+++ b/examples/browser/pretty_printing_with_mathjax.html
@@ -65,13 +65,18 @@
 <input type="radio" name="parenthesis" value="keep" onclick="parenthesis = 'keep'; expr.oninput();" checked>keep
 <input type="radio" name="parenthesis" value="auto" onclick="parenthesis = 'auto'; expr.oninput();">auto
 <input type="radio" name="parenthesis" value="all" onclick="parenthesis = 'all'; expr.oninput();">all
+<br/>
+<b>Implicit multiplication:</b>
+<input type="radio" name="implicit" value="hide" onclick="implicit = 'hide'; expr.oninput();" checked>hide
+<input type="radio" name="implicit" value="show" onclick="implicit = 'show'; expr.oninput();">show
 
 
 <script>
   var expr = document.getElementById('expr'),
       pretty = document.getElementById('pretty'),
       result = document.getElementById('result'),
-      parenthesis = 'keep';
+      parenthesis = 'keep',
+      implicit = 'hide';
 
   // initialize with an example expression
   expr.value = 'sqrt(75 / 3) + det([[-1, 2], [3, 1]]) - sin(pi / 4)^2';
@@ -94,7 +99,7 @@
 
     try {
       // export the expression to LaTeX
-        var latex = node ? node.toTex({parenthesis: parenthesis}) : '';
+        var latex = node ? node.toTex({parenthesis: parenthesis, implicit: implicit}) : '';
       console.log('LaTeX expression:', latex);
 
       // display and re-render the expression
diff --git a/lib/expression/node/OperatorNode.js b/lib/expression/node/OperatorNode.js
index c7d7f0a8a..6316055d3 100644
--- a/lib/expression/node/OperatorNode.js
+++ b/lib/expression/node/OperatorNode.js
@@ -17,8 +17,9 @@ function factory (type, config, load, typed, math) {
    * @param {string} op       Operator name, for example '+'
    * @param {string} fn       Function name, for example 'add'
    * @param {Node[]} args     Operator arguments
+   * @param {boolean} implicit Is this an implicit multiplication?
    */
-  function OperatorNode(op, fn, args) {
+  function OperatorNode(op, fn, args, implicit) {
     if (!(this instanceof OperatorNode)) {
       throw new SyntaxError('Constructor must be called with the new operator');
     }
@@ -35,6 +36,7 @@ function factory (type, config, load, typed, math) {
       throw new TypeError('Array containing Nodes expected for parameter "args"');
     }
 
+    this.implicit = (implicit === true);
     this.op = op;
     this.fn = fn;
     this.args = args || [];
@@ -279,6 +281,7 @@ function factory (type, config, load, typed, math) {
    */
   OperatorNode.prototype._toString = function (options) {
     var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';
+    var implicit = (options && options.implicit) ? options.implicit : 'hide';
     var args = this.args;
     var parens = calculateNecessaryParentheses(this, parenthesis, args, false);
 
@@ -311,6 +314,10 @@ function factory (type, config, load, typed, math) {
           rhs = '(' + rhs + ')';
         }
 
+        if (this.implicit && (this.getIdentifier() === 'OperatorNode:multiply') && (implicit == 'hide')) {
+          return lhs + ' ' + rhs;
+        }
+
         return lhs + ' ' + this.op + ' ' + rhs;
 
       default:
@@ -326,6 +333,7 @@ function factory (type, config, load, typed, math) {
    */
   OperatorNode.prototype._toTex = function (options) {
     var parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep';
+    var implicit = (options && options.implicit) ? options.implicit : 'hide';
     var args = this.args;
     var parens = calculateNecessaryParentheses(this, parenthesis, args, true);
     var op = latex.operators[this.fn];
@@ -384,6 +392,10 @@ function factory (type, config, load, typed, math) {
               case 'OperatorNode:divide':
                 lhsTex = '\\left(' + lhsTex + '\\right)';
             }
+          case 'OperatorNode:multiply':
+            if (this.implicit && (implicit === 'hide')) {
+              return lhsTex + '~' + rhsTex;
+            }
         }
         return lhsTex + op + rhsTex;
 
diff --git a/lib/expression/node/ParenthesisNode.js b/lib/expression/node/ParenthesisNode.js
index dd81dd551..0df0ef7fb 100644
--- a/lib/expression/node/ParenthesisNode.js
+++ b/lib/expression/node/ParenthesisNode.js
@@ -88,7 +88,7 @@ function factory (type, config, load, typed) {
    * @override
    */
   ParenthesisNode.prototype._toString = function(options) {
-    if ((!options) || (options && options.parenthesis === 'keep')) {
+    if ((!options) || (options && !options.parenthesis) || (options && options.parenthesis === 'keep')) {
       return '(' + this.content.toString(options) + ')';
     }
     return this.content.toString(options);
@@ -101,7 +101,7 @@ function factory (type, config, load, typed) {
    * @override
    */
   ParenthesisNode.prototype._toTex = function(options) {
-    if ((!options) || (options && options.parenthesis === 'keep')) {
+    if ((!options) || (options && !options.parenthesis) || (options && options.parenthesis === 'keep')) {
       return '\\left(' + this.content.toTex(options) + '\\right)';
     }
     return this.content.toTex(options);
diff --git a/lib/expression/parse.js b/lib/expression/parse.js
index ef890dc4c..38c08e518 100644
--- a/lib/expression/parse.js
+++ b/lib/expression/parse.js
@@ -896,7 +896,7 @@ function factory (type, config, load, typed) {
         // number:      implicit multiplication like '(2+3)2'
         // parenthesis: implicit multiplication like '2(3+4)', '2[1,2,3]'
         last = parseUnary();
-        node = new OperatorNode('*', 'multiply', [node, last]);
+        node = new OperatorNode('*', 'multiply', [node, last], true /*implicit*/);
       }
       else {
         break;
diff --git a/test/expression/node/OperatorNode.test.js b/test/expression/node/OperatorNode.test.js
index e44e87321..fc73d4f02 100644
--- a/test/expression/node/OperatorNode.test.js
+++ b/test/expression/node/OperatorNode.test.js
@@ -505,4 +505,89 @@ describe('OperatorNode', function() {
     assert.equal(math.parse('1+(1+1)').toTex({parenthesis: 'auto'}), '1+1+1');
   });
 
+  it ('should stringify implicit multiplications', function () {
+    var a = math.parse('4a');
+    var b = math.parse('4 a');
+    var c = math.parse('a b');
+    var d = math.parse('2a b');
+    var e = math.parse('a b c');
+    var f = math.parse('(2+3)a');
+    var g = math.parse('(2+3)2');
+    var h = math.parse('2(3+4)');
+
+    assert.equal(a.toString(), a.toString({implicit: 'hide'}));
+    assert.equal(a.toString({implicit: 'hide'}), '4 a');
+    assert.equal(a.toString({implicit: 'show'}), '4 * a');
+
+    assert.equal(b.toString(), b.toString({implicit: 'hide'}));
+    assert.equal(b.toString({implicit: 'hide'}), '4 a');
+    assert.equal(b.toString({implicit: 'show'}), '4 * a');
+
+    assert.equal(c.toString(), c.toString({implicit: 'hide'}));
+    assert.equal(c.toString({implicit: 'hide'}), 'a b');
+    assert.equal(c.toString({implicit: 'show'}), 'a * b');
+
+    assert.equal(d.toString(), d.toString({implicit: 'hide'}));
+    assert.equal(d.toString({implicit: 'hide'}), '2 a b');
+    assert.equal(d.toString({implicit: 'show'}), '2 * a * b');
+
+    assert.equal(e.toString(), e.toString({implicit: 'hide'}));
+    assert.equal(e.toString({implicit: 'hide'}), 'a b c');
+    assert.equal(e.toString({implicit: 'show'}), 'a * b * c');
+
+    assert.equal(f.toString(), f.toString({implicit: 'hide'}));
+    assert.equal(f.toString({implicit: 'hide'}), '(2 + 3) a');
+    assert.equal(f.toString({implicit: 'show'}), '(2 + 3) * a');
+
+    assert.equal(g.toString(), g.toString({implicit: 'hide'}));
+    assert.equal(g.toString({implicit: 'hide'}), '(2 + 3) 2');
+    assert.equal(g.toString({implicit: 'show'}), '(2 + 3) * 2');
+
+    assert.equal(h.toString(), h.toString({implicit: 'hide'}));
+    assert.equal(h.toString({implicit: 'hide'}), '2 (3 + 4)');
+    assert.equal(h.toString({implicit: 'show'}), '2 * (3 + 4)');
+  });
+
+  it ('should LaTeX implicit multiplications', function () {
+    var a = math.parse('4a');
+    var b = math.parse('4 a');
+    var c = math.parse('a b');
+    var d = math.parse('2a b');
+    var e = math.parse('a b c');
+    var f = math.parse('(2+3)a');
+    var g = math.parse('(2+3)2');
+    var h = math.parse('2(3+4)');
+
+    assert.equal(a.toTex(), a.toTex({implicit: 'hide'}));
+    assert.equal(a.toTex({implicit: 'hide'}), '4~ a');
+    assert.equal(a.toTex({implicit: 'show'}), '4\\cdot a');
+
+    assert.equal(b.toTex(), b.toTex({implicit: 'hide'}));
+    assert.equal(b.toTex({implicit: 'hide'}), '4~ a');
+    assert.equal(b.toTex({implicit: 'show'}), '4\\cdot a');
+
+    assert.equal(c.toTex(), c.toTex({implicit: 'hide'}));
+    assert.equal(c.toTex({implicit: 'hide'}), ' a~\\mathrm{b}');
+    assert.equal(c.toTex({implicit: 'show'}), ' a\\cdot\\mathrm{b}');
+
+    assert.equal(d.toTex(), d.toTex({implicit: 'hide'}));
+    assert.equal(d.toTex({implicit: 'hide'}), '2~ a~\\mathrm{b}');
+    assert.equal(d.toTex({implicit: 'show'}), '2\\cdot a\\cdot\\mathrm{b}');
+
+    assert.equal(e.toTex(), e.toTex({implicit: 'hide'}));
+    assert.equal(e.toTex({implicit: 'hide'}), ' a~\\mathrm{b}~ c');
+    assert.equal(e.toTex({implicit: 'show'}), ' a\\cdot\\mathrm{b}\\cdot c');
+
+    assert.equal(f.toTex(), f.toTex({implicit: 'hide'}));
+    assert.equal(f.toTex({implicit: 'hide'}), '\\left(2+3\\right)~ a');
+    assert.equal(f.toTex({implicit: 'show'}), '\\left(2+3\\right)\\cdot a');
+
+    assert.equal(g.toTex(), g.toTex({implicit: 'hide'}));
+    assert.equal(g.toTex({implicit: 'hide'}), '\\left(2+3\\right)~2');
+    assert.equal(g.toTex({implicit: 'show'}), '\\left(2+3\\right)\\cdot2');
+
+    assert.equal(h.toTex(), h.toTex({implicit: 'hide'}));
+    assert.equal(h.toTex({implicit: 'hide'}), '2~\\left(3+4\\right)');
+    assert.equal(h.toTex({implicit: 'show'}), '2\\cdot\\left(3+4\\right)');
+  });
 });
diff --git a/test/expression/node/ParenthesisNode.test.js b/test/expression/node/ParenthesisNode.test.js
index e2b5c55c1..acd0c79a9 100644
--- a/test/expression/node/ParenthesisNode.test.js
+++ b/test/expression/node/ParenthesisNode.test.js
@@ -129,6 +129,7 @@ describe('ParenthesisNode', function() {
     var n = new ParenthesisNode(a);
 
     assert.equal(n.toString(), '(1)');
+    assert.equal(n.toString({}), '(1)');
   });
 
   it ('should stringify a ParenthesisNode when not in keep mode', function () {
@@ -158,6 +159,7 @@ describe('ParenthesisNode', function() {
     var n = new ParenthesisNode(a);
 
     assert.equal(n.toTex(), '\\left(1\\right)');
+    assert.equal(n.toTex({}), '\\left(1\\right)');
   });
 
   it ('should LaTeX a ParenthesisNode when not in keep mode', function () {
diff --git a/test/expression/parse.test.js b/test/expression/parse.test.js
index fcad09711..ef2ee87a6 100644
--- a/test/expression/parse.test.js
+++ b/test/expression/parse.test.js
@@ -1084,9 +1084,21 @@ describe('parse', function() {
       assert.deepEqual(parseAndEval('[1,2;3,4] [2,2]', {A: [[1,2], [3,4]]}), 4);  // index, no multiplication
     });
 
+    it('should tell the OperatorNode about implicit multiplications', function() {
+      assert.equal(parse('4a').implicit, true);
+      assert.equal(parse('4 a').implicit, true);
+      assert.equal(parse('a b').implicit, true);
+      assert.equal(parse('2a b').implicit, true);
+      assert.equal(parse('a b c').implicit, true);
+
+      assert.equal(parse('(2+3)a').implicit, true);
+      assert.equal(parse('(2+3)2').implicit, true);
+      assert.equal(parse('2(3+4)').implicit, true);
+    });
+
     it('should correctly order consecutive multiplications and implicit multiplications', function() {
       var node = parse('9km*3km');
-      assert.equal(node.toString({parenthesis: 'all'}), '((9 * km) * 3) * km');
+      assert.equal(node.toString({parenthesis: 'all'}), '((9 km) * 3) km');
     });
 
     it('should throw an error when having an implicit multiplication between two numbers', function() {
@@ -1849,8 +1861,8 @@ describe('parse', function() {
     it('should correctly stringify a node tree', function() {
       assert.equal(parse('0').toString(), '0');
       assert.equal(parse('"hello"').toString(), '"hello"');
-      assert.equal(parse('[1, 2 + 3i, 4]').toString(), '[1, 2 + 3 * i, 4]');
-      assert.equal(parse('1/2a').toString(), '1 / 2 * a');
+      assert.equal(parse('[1, 2 + 3i, 4]').toString(), '[1, 2 + 3 i, 4]');
+      assert.equal(parse('1/2a').toString(), '1 / 2 a');
     });
 
     it('should correctly stringify an index with dot notation', function() {
diff --git a/test/function/unit/to.test.js b/test/function/unit/to.test.js
index 083ef0c6d..b0849fc37 100644
--- a/test/function/unit/to.test.js
+++ b/test/function/unit/to.test.js
@@ -83,6 +83,6 @@ describe('to', function() {
 
   it('should LaTeX to', function () {
     var expression = math.parse('to(2cm,m)');
-    assert.equal(expression.toTex(), '\\left(2\\cdot\\mathrm{cm}\\rightarrow\\mathrm{m}\\right)');
+    assert.equal(expression.toTex(), '\\left(2~\\mathrm{cm}\\rightarrow\\mathrm{m}\\right)');
   });
 });