Relying on your brain to do some things which machines can do is a great way of improving your brain’s retentiveness and also boost your self-esteem. In choosing to write this article, I have decided to share some age long methods of mental mathematics that I have been using since I was a young child and still use when I’m on the hot seat during examinations or in a meeting or when I want to look cool as sh*t.
- The first type of mental math I would like to demonstrate is mental addition. Ever had to add big sums without a calculator or a pen and paper only to make a silly mistake? The best of us make mistakes but that doesn’t mean we can’t try our best to reduce the said number of mistakes. Without too much story;
- Add 323 and 519
- First of all add 300 and 500.
- 300 + 500 = 800
- Then add 23 and 19 (this is where it gets a bit tricky)
- Take ‘1’ from 23 and add it to 19.
- This gives 22 + 20 = 42 (which is easier to add than 23 + 19) even though they give the same results.
- Now add 42 + 800 = 842
- This is much easier than doing “nine plus three equals twelve; write two, carry one, two plus one is three….”
- Let us try the same thing for 199 and 744
- 100 + 700 = 800
- 90 + 40 = 130
- 9 + 4 = 13
- 800 + 130 + 13 = 943
- Easy right?
- Try a bit yourself 214 + 441; 6743 + 188;
- The next type is mental multiplication. This follows basically the same pattern as mental addition but let me illustrate with one example.
- 20 x 17
- First of all, multiply 20 and 10
- 20 x 10 = 200
- Then multiply 20 and 7
- 20 x 7 = 140 (2 x 7 equals 14; just add a zero at the back)
- 200 + 140 = 340
- 20 x 17 = 340.
- Try 14 x 12; 22 x 8
This is a very good way to massage the ol’ gray matter and also to look cool as shit.
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