Math is not that bad. Addition and subtraction? That’s easy. Multiplication of single-digit numbers? Elementary. But let’s admit it: when it levels up to multiplying two two-digit numbers, we’re doomed.

A Mathematician used his talents and posted this Math trick on how to quickly multiply two two-digit numbers like a pro.

Multiplying two two-digit numbers

You’ll be surprised how easy it is. Let’s look at his example of 21 multiplied by 31.

First, multiply the first two digits and place the product as the first number. Leave a blank in the middle. Then, multiply the last two digits and write the product down. At this point, you must have 6_1. Did you get it?

To get the middle number (it could get pretty tricky), multiply the inner and outer numbers. Then, add those two products.

So, that’s 2×1 = 2 and 1×3 = 3; add the two, and you have 5. Place it in the blank, and you get 651! Don’t believe this? Get a calculator and see for yourself.

When the middle number exceeds 9

That was just level one of it. Let’s step it up a notch. Let’s do 43 multiplied by 21.

Go ahead and solve this by doing the same process. So 4×2 = 8. Write that down and leave a blank in between. Then 3×1 = 3, and you have 8_3.

For the middle number, do the same trick: 4×1 = 4 and 3×2 = 6. However, when you add them, you get a 10 and only have room for one number.

Don’t worry; this trick would still work. Remember what we do with addition? We bring down or copy the second digit (which is 0) and carry over the first digit (1) to the following number (8) and add them. You will have 903!

Double-digit first number

Here’s another one: 42×63.

Again, follow the same process. 4×6 is 24. You don’t need to worry if the product of multiplying the two first digits would be a double-digit number; you simply have to copy that. Again, leave a blank in the middle. Then multiply 2 and 3, and you get 6. You have 24_6.

For the middle number, 4×3 = 12 and 6×2 = 12. Add the two, and you have 24. Following the previous rule, bring down the second digit (4) and carry over the first digit (2) to the number at the left. In this instance, you add it to 4.

Did you also have 2646 as your answer? If yes, that means you’re getting better. Ready for the next one?

Two-digit last number?

TecMath did not discuss this, but what if the product of the two second digits is also double-digit? I’ll solve this one for you. (Yes, yours truly!) Let’s take 37×26 as an example.

Multiply the two first digits (3×2), and you have 6. Write it down and leave a blank. Now, multiply the two second digits (7×6), and you have 42. Write down the second digit (2, while you put the first digit (4) “on hold” while you wait for your middle number.

Solve for the middle number – so that’s 3×6 = 18 and 7×2 = 14. Your sum would be 32. Now, add the first digit you put “on hold,” and you’ll get 36. Follow the same rule on a two-digit middle number, and you’ll get 962!

Practice with these numbers, and you’ll surely get the hang of it.

Please SHARE this with your friends and family.

Source: techmath YouTube Channel