I also use this method when teaching students how to factor trinomial expressions. See figure 8’s diagram. For example, to factor …………………, students can reverse the algorithm. First, they find number to put in the t and ones columns such that the product of the numbers in the t column is 3, and the product of the number in the ones column is 4 . then student must check to see that the sum of the number in the diagonals is indeed 8. If so, they can write the solution. If not, they must guess new number to put in the column. One incorrect and the correct solution are shown in figure 8.