Is it odd that almost every startup I or my friends have interviewed with refuse to answer the "number of outstanding shares" question? Have others had similar experiences?
If a company won't tell you enough to calculate the percentage, that's like you asking "What's your offer for salary?", "Dollars. Definitely dollars.", "Can you be more specific?", "No. We consider exact salary offers to be competitively sensitive."
~ $2,000,000 if they've only issued 500,000 shares ~ $100,000 if they've issued 13,000,000 shares ~ $2,000 if they've issued 40,000,000 shares.
And your returns would be negative for any greater number of shares.
The real problem is that you don't know the price per share from the current valuation.
Not that an at-the-money option has no value -- but I think for tax purposes, it's not treated as such.
On the other hand, any company that gives you no information on the number of outstanding shares makes their options worthless as compensation. You should let them know this on your way out the door.