Transcription
Before we start this video, in 5 seconds, can you quickly tell me how much is 86 * 84? It is 7224. I know many of you would have struggled to find it in 5 seconds, but I am making a series of mental math videos, and after completing this series and with a bit of practice, you will be able to do calculations like these faster than a calculator, that is at a lightning fast speed. Yes, yes, even faster than the snap of Thanos, and you will be able to amaze your friends and appear smarter in front of them.
Okay, so are you ready? We will first start with the very basic, which is multiplying any two-digit number with 11. How would you multiply 43 with 11? Yeah, I know we can use the method we had learned in school, but it will be a bit longer. But using this trick, it will be super fast. So, write four and three, and in the center, write 4 + 3 or 7. That's it. Answer is 473. Although it's basic, but it's super fast. Now, 54 * 11. Write five and four, and in between, write 5 + 4 or 9. Amazing.
But you might wonder, what if the sum is greater than or equal to 10? Like 68 * 11. Write 6, then 8, and in the middle, it will be 6 + 8 or 14. So, take one to the carry and add with six to make it seven. So the answer is 748. See, lightning fast. Now you might be thinking that I am sharing tricks only for specific numbers, but that's not mental math. Don't worry, this is only the beginning. As this is the first part, there are many more such tricks to come.
Now, the trick I taught you also works with three-digit numbers. For example, 352 * 11. Write three and two. Now, in the center, first add both of them to get eight, and now add 5 + 2 or 7 here. That's it. We get 3872. And if the sum is greater than 9, then just carry like the previous one. For example, 574 * 11. So, write five and four here. Then, in the middle, write 5 + 7 or 12, and here 7 + 4 or 11. Now, carry one here to make it six, and then carry one here to make it three. So the answer is 6314. Awesome. We are still faster than the calculator.
Now, let us move to the next trick, which is multiplying two two-digit numbers with the same first digit and ending in five. Like, multiply 75 * 75 in 5 seconds. You might be blank right now, am I correct? So, the trick here is to multiply seven with the next number or eight to get 56, and then simply add 25 to it. This will be 5625. Okay, now try 35 * 35. 3 * 4 is 12, and then add 25. That's it. Faster than a calculator, isn't it? Now, tell me in the comments, what will be 95 * 95? Great.
Now, are you ready for the next trick? It is multiplying two two-digit numbers with the same first digit of both the numbers, and the sum of the ending digits is 10. For example, 44 * 46. Here, the first digit of both the numbers are the same, which is four, and the sum of the ending digits is four + 6 or 10. Now, do four * its next number or five, which is 20, and then 4 * 6 or 24. So the answer is 2024. Isn't this cool? Now, let us try 67 * 63. 6 * 7 is 42, and 7 * 3 is 21. So we get 4221. Awesome. We're still beating calculators in speed. Okay, now tell me in the comments, what will be the value of 89 * 81? You are already doing calculations faster like a human calculator.
Lastly, don't forget to practice this trick, and you'll get even faster. If I get 10,000 likes on this video, I will make part two of it, which will be much more interesting and super fun. So, good. [Music]