Before doing the calculation, first check your online broker site. The amount you need to withdraw may be there. For example, with Schwab, just click "Balances" and scroll to the bottom to find:
Done! At least for this account.
Because this is the first RMD, it doesn't have to be taken until 4/1/2014; but next year's RMD will need to be taken by 12/31/14.
Note the footnote link to a calculator for distributions required from inherited IRAs!
An easy-to-use calculator for the DIYer is provided by FINRA. Only 2 inputs required: previous year balance and age.
The results then are shown as: