Tag Archives: intuition

Test your intuition: bijections

Suppose we have sets and and a function (that is, ’s domain is and its codomain is ). Suppose there is another function such that for every . Is necessarily a bijection? That is, does necessarily match up each element … Continue reading

Posted in logic | Tagged , , , | 12 Comments

Minus times minus is plus

I’ve seen several recent posts wondering about an intuitive explanation for the fact that “a minus times a minus equal to a plus”. I understand why people would wonder about this—the way it’s often taught, it seems to be just … Continue reading

Posted in arithmetic | Tagged , , | 14 Comments

Carnival of Mathematics and other links

The 47th Carnival of Mathematics has been put together by jd2718; go give it a read! Some of my favorite posts include factoring by puzzles, teaching binary numbers, the 2009 game, cliques of dichotomies, but there is lots of other … Continue reading

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