Multiplying with Lines
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An alternative to the traditional way of multiplying two numbers. Take the digits of the first number and draw sets of vertical lines corresponding to each digit; then do the same with the digits of the other number, but draw the horizontal lines. Next, count the intersections of each pair of sets of lines (red points and green labels). Finally, add the numbers between diagonals from right to left (in blue). This procedure is equivalent to the usual "long multiplication" method (right).
Contributed by: Enrique Zeleny (March 2011)
Open content licensed under CC BY-NC-SA
"Multiplying with Lines"
Wolfram Demonstrations Project
Published: March 7 2011