Is there a faster way to multiply by 11? What about 14? Let's take the following example: 1412 x 14 = 19768 The technique helps you finding digits from left to right as following: take the first digits of 1412…

## Find the square of a number (nearing to 100) in head

How much is 5 Â² ? How about 12 Â² ? Well, if you have already finished the gymnasium then maybe you are already used to find the square for these numbers. But how about 104 Â² ? I found…

## Fast multiplication n-digits (on certain situations)

I've found a solution for fast multiplication n digits with respect to the following conditions: have the same number of digits the first digit of both numbers are equal the sum of last digit of both numbers is 10 Example…

## Fast multiplication by 11

One of my favourite techniques is that which allows us to fast multiplication by 11. To get your attention I will say that I can multiply in my head the following numbers: 748346274 x 11 = 8231809014 The technique is…

## Fast multiplication 3 digits

Are you scared when comes to multiply a product like 123 x 321 in your head? Well, that's not so hard as it seems to be! Fast multiplication 3 digit For this we can use a technique which reduce the…

## Fast multiplication 2 digits

How do you calculate how much is 93 x 97 in your head? Sounds that impossible? There are many quick algorithms depending on the nature of the numbers you want to multiply. In some situations fits better one algorithm, in…