Ancient Egyptians were really good at Math - an easy way to multiply two numbers

Did you know that the Ancient Egyptians were really good at Math?

Here, I'll show you one very clever trick they used for multiplication.
There's also a video from youtube at the end, so you can watch that if you feel the instructions here are not good enough.

(pixabay.com)

Instructions

Take two numbers to be multiplied - I will use 17 and 25 as those are the numbers used in the accompanying video.

So, we have,

17 x 25

Step 1

With the first number (17) we need a list of numbers, starting at the number one, which doubles each time:

1
2
4
8
16
32
etc.

Next, we find the numbers in that list which, when added together will equal the number, i.e. 17.

1 + 16 = 17, so we have

(1)
2
4
8
(16)
32

Step 2

With the second number for our multiplication (25), we make a list which doubles each time, but this time using 25 as the starting number:

25
50
100
200
400
800
etc.

We now put the two lists side by side:

(1).....................25
2.......................50
4.......................100
8.......................200
(16)...................400
32......................800

Step 3

Finally, we see which numbers in the second list correspond with the ones which we 'found' from the first list in Step 1 - that is the numbers in the second list which correspond to the numbers 1 and 16.

25 corresponds to 1, and
400 corresponds to 16

We get the answer by adding these two numbers, 25 and 400 = 425

Therefore,

17 x 25 = 425

Here's the link to the youtube video:

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Thanks for looking at my post and..

(pixabay.com)

... be happy!

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