In this video, Motley Fool analyst Andrew Tonner focuses on the key number that investors need to understand at Apple. That number is 6, which is the company's price-to-cash flow ratio. Even though Apple's market cap is around $400 billion, the market is currently valuing Apple at around $263 billion, as the rest of its capital value is tied up in cash and investments.

Apple made around $56 billion in cash from its operations, and stripping out the productive expenditure makes it around $42 billion. Comparing the cash to Apple's market cap means that the company is trading at around 6 times the cash flow, which is significantly low.

Andrew also mentions Apple's growth opportunities, including the potential for a low-cost iPhone and the iWatch. Considering the company's growth opportunities and after eliminating any market noise and estimates, Andrew says Apple seems like a very cheap company trading at $400. Check out the video for more details.

Andrew Tonner owns shares of Apple. The Motley Fool recommends and owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.