A COOL MATH METHOD: LATTICE MULTIPLICATION

I dropped by the CoolMath4kids site while on the way to find best ideas to teach Mew basic math skills and found out the Lattice Multiplication, a super cool math method which I am sure will get a hit for any student scare of doing 2-digit or even more multiplication problem.

Googling the phrase of Lattice Multiplication yielded me further information about this method.
According to Dr.Math, "the Lattice Form of Multiplication (the official name for this method) dates back to the 1200s or before in Europe. It gets its name from the fact that to do the multiplication you fill a grid which resembles a lattice one might find ivy growing on".

While we are all familiar with the regular method of multiplication that always takes 2 steps: multiply and carry altogether, then add, the lattice method does breaks the multiplication process into 3 separate smaller steps, hence a lot of students (including myself) find it really easier! Put it simple, lattice multiplication is a method of multiplying large numbers using a grid. Digits to be carried are written within the grid, making them harder to miss.

LEARN NC, a program of the University of North Carolina at Chapel Hill School of Education, demonstrates step-by-step this useful method as follows:

- First, draw a grid that has as many rows and columns as the multiplicand and the multiplier.
- Next, draw a diagonal through each box from upper right corner to lower left corner. Continue the line a short way past the grid.
- Write one factor across the top and the other down the right side, lining up the digits with the boxes.
- The multiplication is performed by multiplying the digits at the head of each row and column. Fill in each square of the grid with the product of the digits above and to its right, recording the products so that the tens are in the upper (diagonal) half of the square and the ones are in the lower half.


If the product does not have a tens digit, record a zero in that triangle.

- Now add the numbers in the grid along the diagonals, starting from the lower right corner. (“ride the slide.”) Carry any tens into the top of the next diagonal.

- To find the answer, read the digits starting down the left of the grid and continuing across the bottom.


More interestingly and importantly, lattice multiplication can easily be extended to multiply decimal fractions. Suppose, we want to multiply 2.314 by 1.57. We would proceed as before, but draw lines from the decimal points down and to the left until they meet, then follow the diagonal to the left or bottom of the grid. The point where this diagonal emerges from the grid is the position of the decimal point in the answer.