The Japanese math trick is easy to use. For example, if you want to multiply 12 by 24, you draw one line diagonally from bottom left to top right, representing the first ten in the number 12. Move over a space and draw two more diagonal lines parallel to the first one for the two ones in 12. Next, draw two diagonal lines crossing over the first lines, representing the two tens in 24. Draw the lines at the lower left of the page, creating the bottom of what will be a diamond. Move up a space and draw four more lines, representing the four ones in 24.
When you are done drawing all the lines, you will have a diamond shape with many lines. Now count the places where the lines intersect. Count each intersection in the right corner of the diamond. In the 12 times 24 example, there will be eight points of intersection on the right corner. Now, count the points of intersection on the left. There should be two. Finally, count the points of intersection on the top and bottom of the diamond. There should be a total of eight. Put the number in order from left to right, 288, as your answer. Checking with a calculator, you will see that 12 times 24 is indeed 288.
When you work in triple digits or more, there is a special trick for calculating them. For example, when you multiply 123 by 321, you create three sets of lines. Start with one diagonal line at the top, from bottom left to top right, move down and draw two more, then move down and draw three more. Work in reverse and draw three lines going across the bottom, then two more up a space, then one at the top. You will count five sets of intersecting lines: Far left, inside left, middle, inside right and far right. In this example, you will have 3, 8, 14, 8 and 3. Since 14 cannot be a number in a sequence, so you will add the 1 to the number to its left so that you only have single digits across the board. Your answer will then be 39,483. Keep adding numbers to the left to achieve all single digits; if you have to add a one to a 9, creating a 10, you would then add a one from that column to the left, leaving behind a zero.
Though the Japanese math trick may seem like a bit of magic, it is rooted in good old-fashioned mathematics principles. Math teacher Presh Talwalkar explains that each line is a placeholder representing a power of ten. The math gets tricky, but Talwalkar says that using the trick gets you the same results as writing out the equation like this: 12x24=(1x10+2)(2x10+4). Of course, it's easier just to use the lines trick or to just do the multiplication by hand.