This question figured in a basic maths exam which 96% of primary teachers gave the wrong answer, the correct one being 'infinity'. Now this is obviously cobblers. But a letter to today's Observer claims that the right answer is 'there is no solution to this equation', and gives a persuasive argument to this effect - whatever you multiply or divide zero by, it remains zero.
I say double cobblers. The right answer is 'two'. 'Zero' is just notational shorthand for 'the absence of number', or 'nothing' if you prefer. 2 + nothing = 2. 2 x nothing = 2. I rest my case.
Any mathematicians out there?