Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies.

Quick, what's 54 / 3? How about 324 / 6?

Wait, don't go searching for your calculator or smart phone—believe it or not, you can do these problems and countless others quickly and easily in your head.

In Part 1 of our mental division series, we learned the first 3 tips to becoming a mental division maestro. Today we're going to finish things off with the 2 most powerful mental division tips that are sure to help you kick your calculator dependency forever.

Tips #1-3 Recap
If you haven't yet absorbed, practiced, and perhaps even fallen in love with the first 3 mental division tips that we talked about last time, I highly encourage you to do that before continuing to today's tips. As you'll see, the tricks and tips for today build upon those that we talked about last time, so your efforts will be doubly rewarded.

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