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Are you good with mental calculations? I certainly wasn’t. I always had issues with even the most basic problems. My confidence really took a hit because it would take me ages to answer a simple math question, like how much change someone needed, or how we’d split a bill.
It affected me in a lot of ways, but I never took any steps to get around it. I just chalked it up to being bad at mental math. Not too long ago, I had a couple of interview rounds in which passing a mental math assessment was a requirement. Knees week, heart in my throat, I took the tests, and failed spectacularly.
I missed the benchmark by a mile both times and knew that I had to do something if I wanted a job in the industry. That’s how I began my latest experiment: improving my mental arithmetic.
If improving your mental math skills is something you want or need to do, you might want to try the approach I took.
Here’s how I got started:
I downloaded a mental math app on my phone and started doing the practice problems during my morning commute on the train.
The app I use is called Math: Mental Math Games, although there are a lot of other options out there if you’re looking for one. I like this particular one, because there are a couple of features that I find quite useful, like the helpful tips section that demonstrates techniques or shortcuts that you can use to speed up your calculations.
There are different modes, but I tested myself on speed to figure out my benchmark. The speed training has a set of ten problems, and a timer, to track your performance.
I was shockingly slow at even the most basic level. I’m not kidding, I’m pretty sure this was preschool math and there are toddlers who would’ve gleefully decimated my time, taken a nap, and woken up to find me still struggling with the questions.
I started by taking note of the time it took me to answer the ten problems on day one. This is something you should do if you’re going to try this yourself, or you won’t know how much you’ve improved.
My time was over 30 seconds on the ten single digit subtraction and addition problems. I had a lot more difficulty on the double digit addition and subtraction problems, with an average time of almost two minutes, and over five minutes on the triple digit problems.
So here’s a quick summary for easy comparison:
Time taken to complete 10 problems
- Single digit subtraction and addition = 30 seconds
- Double digit subtraction and addition = 2 minutes
- Triple digit subtraction and addition = 5 minutes
- Double digit multiplication = N/A
Yeah, it took me an average of three seconds to answer a problem like “7 + 9”. For double digit multiplication problems, like “43 * 57”, I didn’t have a benchmark time. I was so bad at them, I couldn’t complete the ten problems at all.
The results of the experiment
After just a couple of days of practice, my speed was a lot better. It’s now been over a month, and my average times are as follows:
Time taken to complete 10 problems
- Single digit subtraction and addition = 8 seconds
- Double digit subtraction and addition = 30 seconds
- Triple digit subtraction and addition = 50 seconds
- Double digit multiplication = 2 minutes 40 seconds
I know these times are nothing to be bragging about, especially my time on the multiplication questions, but it’s a major improvement for someone who couldn’t answer them at all just over a couple of weeks ago.
This is good news if you’re looking to attempt this yourself, because I noticed that improvement occurs quite quickly.
Tricks and technique
Improving your mental math skills isn’t just a matter of attempting a bunch of questions on repeat. A few simple tweaks can really improve your ability to perform calculations in your head.
Schools tend to teach math in a way that’s clunky and impractical for quick mental calculation. For instance, most of us were taught to do math from right to left, but it’s far more natural to do it from left to right, especially when calculating mentally.
I used a combination of the app mentioned above, and an online course from The Great Courses, The Secrets of Mental Math. I found the online course to be especially useful. It’s well structured and the techniques are explained in full.
I can now calculate the square of any double digit number in my head — something that I always thought would be impractical because I would be too slow at it.
If you decide to give the course a go, you’ll probably find the presentation of the course to be quite cheesy, but the content is practical and very helpful. This isn’t a paid advertisement or anything, it’s just a recommendation I’m making because I found it worthwhile. The course is often on discount, so I’d suggest waiting for the sale.
If you’re interested in improving your mental math even further, you may want to consider learning the soroban or Japanese abacus.
I tried my hand at learning the abacus, and while I’ll need lots more practice, I have noticed that the abacus offers a couple of significant advantages over regular mental arithmetic:
- There’s significantly less cognitive load:
- Consider trying to add the numbers 74, 986 and 17, 239 mentally. I’m sure you could do it, but I’ll bet keeping those numbers in your head will be a challenge in itself.
- The beads on the abacus provides a visual form to the numbers and allows you to hold the numbers in your head with less strain on your memory.
- It’s a lot quicker:
- I’ve found that the using the abacus is like executing an algorithm to solve math problems. You barely have to think about the numbers, because the calculations become part of your muscle memory.
- This factor, combined with the lower cognitive load, makes you a lot faster. It’s almost impossible to articulate, so you’ll have to try it yourself to know what I mean.
If you want to learn the abacus, you can certainly do it online. There are many options available, but as I haven’t used them myself, I won’t make any recommendations.
As it turns out, I’m no longer trying to apply for the job that required mental math skills, but sharpening the skill was definitely worthwhile. I’m going to continue working on my abacus skills too, perhaps at a more leisurely pace.
Mental math can come in handy in ways most people wouldn’t necessarily think of. Par exemple, if you’re quick with math and have some knowledge of basic probabilities, you could improve your odds of winning at poker. Those game nights could become a lot more fun with a couple more tools under your belt.
I hope you’ve found this useful, and if you do decide to give this a go, keep me updated on your progress! If you’ve found other ways to improve your mental arithmetic, leave a comment and let me know how you did it.