5 Tips for Faster Mental Division (Part 1)

Have you ever wished you could divide numbers quickly and easily in your head? Believe it or not, you can! Over the next two weeks, we'll be learning my top 5 tips to help you become a mental division maestro.

Jason Marshall, PhD,
July 27, 2013
Episode #163

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Mental DivisionIf you're anything like me, you don't exactly love doing long division. Which is exactly why I avoid it as much as I can. Of course, one way to avoid doing division the old fashioned way with paper and pen is by using a calculator. Most of the time, that's exactly what I do.

But the truth is that sometimes calculators—or phones with calculators—are inconvenient. And sometimes you need to do division right there on the spot in your head. How can you do it? Keep on reading to learn 5 simple things that you can do to take your mental division skills to the next level..


Tip #1: Approximate If You Can

The first thing you can do to speed up a lot of the mental division problems you'll encounter is to stop and think about just how accurate you need the answer to be. Sometimes you need an exact answer, or perhaps an answer that's accurate to two decimal places, or three decimal places, or something else specific like that. But a lot of the time you really just need a ballpark estimate.

If you only need an approximate answer, don't waste time figuring out the exact answer…make a quick and dirty estimate instead.

In those cases where you only need an approximate answer, don't waste your time by figuring out the exact answer. Instead, make a quick and dirty estimate. How? Well, let's say you work in a coffee shop and you want to figure out the average amount spent by your customers. So far you've collected $164 from 26 people. What's the average—or more technically the mean—bill? Well, $164 is pretty close to $150, and 26 people is pretty close to 25 people. So instead of calculating $164 / 26 people, let's start by calculating something that's close to that: $150 / 25 people. That's a much easier problem to solve! It says that the answer is roughly $6 / person.

No, this technique doesn't give exact values, but if you estimate wisely it'll give you answers that are pretty close…and with a fraction of the work.

Tip #2: Simplify Before You Start

The rest of today's tips are all things that you can do when an approximate answer just isn't good enough. When faced with such problems, the first thing you should do is...


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