The Egyptians
performed multiplications by a procedure which was half decimal, half binary.
Let suppose
we want to multiply 43
by 237
Let’s make
a table.
In the
first line , 2nd column place 1 and in the
3d column 237
In the
following lines, multiply by 2 the numbers of the previous line.
Now 43 =
32 + 8 + 2 + 1 : so it means that we need the lines with a
cross in the first column
|
X |
1 |
237 |
|
X |
2 |
474 |
|
|
4 |
948 |
|
X |
8 |
1896 |
|
|
16 |
3792 |
|
X |
32 |
7584 |
|
|
Etc… if needed |
|
|
|
|
|
Make the
sum of the numbers of the 3d column for the lines with a X.
237 + 474 +
1896 + 7584 = 10191 , this is the result !
Hence, the
Egyptians just needed to know to multiply by 2. Nice, isn’t it
?
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