When you give a taxi driver an address, always specify the cross streets. New Yorkers, even most cab drivers, probably wouldnt know where to find 994 Second Ave., but they do know where to find 51st and Second. If youre heading to the restaurant Le Bernadin, for example, tell them that its on 51st Street between Sixth and Seventh avenues. The exact number (in this case, no. 155) is given only as a further precision.
If you have only the numbered address on an avenue and need to figure out the cross street, put new batteries in your calculator and refer to the address locator in the front of the Yellow Pages.