title: Python - Pymongo MongoDB 3.4 - NumberDecimal
body: <p>i am using mongodb 3.4 in order to insert proper prices to my database..</p>
  
  <p>According to:</p>
  
  <pre><code>https://github.com/mongodb/specifications/blob/master/source/bson-decimal128/decimal128.rst#reading-from-extended-json
  </code></pre>
  
  <p>i used this in my python code:</p>
  
  <pre><code>'credits': {'$numberDecimal': Decimal128('9.99')},
  </code></pre>
  
  <p>but throws:</p>
  
  <pre><code>bson.errors.InvalidDocument: key '$numberDecimal' must not start with '$'
  </code></pre>
  
  <p>So what is the correct syntax for inserting numberdecimal in mongodb using python ?</p>
  
  <p>thanks and greetings</p>