DM Blog

Math — Left to Right


Have you ever considered why we’re taught to read from left-to-right, but when it comes to math, we’re taught to do it from right-to-left? (The one exception being “long division” of course, which we’re taught to do from left-to-right from the start.)

A long time ago I started forcing my mind to do math from left-to-right instead and I’ve found that not only is it much faster, but it’s also much easier.

The idea of doing math from right-to-left might make more sense on paper, but if you’re doing it in your head and need to find the right answer on the spot, then doing it from left-to-right is by far the best way. It does take a little getting used to and I wouldn’t expect it to be easy right away, but I definitely think you’ll find it much easier (and faster) if you stick with it for a while…

To illustrate this concept (or at least left-to-right subtraction), here’s a video I found on YouTube:

Left-To-Right Subtraction: Speed Math / Fast Math

The idea for this article came when we ordered pizza the other night, and for the first time in a long time, I asked Michelle to go to the door and pay (me going to the door would have involved putting pants on, and it was way too hot for that). When the pizza delivery guy got here, Michelle went to the door right away while I wondered what was taking so long. And then it occurred to me that maybe Michelle was having a hard time figuring out how much to tip the guy. It turned out I was right – he ended up taking the debit-at-the-door machine from her, asked how much she wanted to the total to be, and entered the tip amount for her…

This is a common scenario/problem I see people having all the time. The problem is that we’re asked to enter numbers from left-to-right, but we’ve been taught to do math from right-to-left. The solution is simple – learn to do math from left-to-right instead and forget what they taught you in school. In fact, schools should probably start teaching math from left-to-right instead!

When I originally had the idea for this article, I started planning a whole bunch of examples, an in-depth explanation of what I’m talking about and tips on how to start training your mind to do math from left-to-right, but after I came across that video on YouTube, I realized – it’s all already been done before, and they’re probably already doing a better job explaining it than I would do, so, no examples… But I strongly recommend that you look it up on Google and have a deeper look at it. You’ll thank me later.

Like I briefly mentioned above, that YouTube video only shows subtraction from left-to-right, but it’s completely possible to also do addition, multiplication and division from left-to-right as well. Actually, it’s not only possible it’s actually better