Procedures for a 2 by 2 Lattice

These procedures are for a problem like 27 X 32.

First draw a box about 2 inches by 2 inches.

Divide the box into four equal boxes.

Divide each of those boxes diagonally from the top right to the bottom left.

Write the tens digit of the first number over the top left box. (put the 2 from 27 over the top left box.)

Write the second digit of the first number over the top right box. (put the 7 from 27 over the top right box.)

Write the first digit of the second number to the right of the top right box. (put the 3 from the 31 to the right of the top right box.)

Write the second digit of the second number to the right of the bottom right box. (the 1 from 31 would go to the right of the bottom right box.)

Multiply the number above the top right box by the number to the right of the top right box. (multiply 7 times 3)

Write the product (answer to the multiplication problem) in the top right box, where the top half of the box is the tens digit, and the bottom half is the ones digit. (Put 2 in the top half and 1 in the bottom half because 7 x 3 =21)

Multiply the number above the top left box by the number to the right of the top right box. (multiply 1 times 3.)

Write the product in the top left box. (Put the zero in the top half, and the 6 in the bottom half because 1 x 3 = 3.)

Multiply the number above the top right box by the number to the right of the bottom right box. (Multiply 7 times 2.)

Put the product in the bottom right box. ( Put the 1 in the top half and 4 in the bottom half because 7 x 1=7)

Multiply the number above the top right box by the number to the right of the bottom right box. (multiply 1 x 2)

Write the product in the bottom left box.. (Put the 0 in the top half and 4 in the bottom half because 2 x 1=2)

Then add the number in each colored area together. (such as the 2 and 1 are in a blue section, add them together to get the sum of 3).

Then put the answer together in each colored section and write it underneath (such as a 2 + 0 + 1 = 3, write that underneath the colored section).

If you have to carry, put the number in the next colored section.

Then read from the top left to the bottom right.