How to Multiply Large Numbers Quickly With the Box Method

If you ever need to multiply large numbers quickly and without the hassle of the standard method you can use the box method:This is also called the lattice method of multiplication.

Steps-Get a piece of paper. Graph paper is best but if not make a grid on the paper.

Draw lines diagonally through certain boxes going down and to the left as in the illustration.

Write one of the factors on the top of the grid, one digit in each box, then the other on the right in the same way.

The factors, in this case 371 and 492.

In each of the halved boxes multiply the two digits that correspond with the box, the ones that would be its coordinates in a grid map. Put the tens digit on the top left side of the line and the ones digit on the bottom right side. If you end up with a one digit answer write a zero as a placeholder where you would have put the tens digit.

                           

Add up the digits in each diagonal column formed by the diagonal lines

The final product. Obtained after addition. In this case the product (answer) is 182,532


You should make the grid large enough so that you don't have trouble figuring out what is where later.

You can do this with any size number, but the larger the number the larger the piece of paper you will need.