Now that the fall term of school is over, we can all relax for the holidays. Here’s a gift to everybody out there, students and teachers and especially parents, who might still be befuddled about some of the more puzzling things that came up in math class. This is why the teacher said what she said.

1) You can’t divide by 0.

Why not? Well, because if you try to, no matter what answer you write down, it won’t make sense. Take 6 divided by 0. What should that equal? A lot of people guess 0. But that doesn’t work. If 6 divided by 0 were equal to 0, that would mean that 0x0 would have to equal 6 (just as 6 divided by 2 equals 3 means that 2×3 equals 6). The trouble here is that 6 divided by 0 cannot equal any number, because any number times 0 always gives 0, not 6. This is why division by 0 is verboten.

2) 1 is not a prime number (more…)