Update: As Carlos said, you can check before you do the division. The method I showed - comparing with 1/0 - is especially useful if you got results of a division in a table field, and want to check for this kind of invalid data.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
