The Grid Method of Multiplication for Parents

The standard method for multiplying together two numbers with two or more digits is usually called long multiplication. However a simpler method, which is easier to understand, and which uses easier calculations, is now taught in schools. It is sometimes referred to as the Grid Method. The Grid Method is based on the idea of splitting both numbers being multiplied, into their tens and units. We will illustrate the method by calculating 23 x 42, the 23 becoming 20 + 3 and the 42 becoming 40 + 2. Imagine a rectangular array of counters, with dimensions 23 x 42. The total number of counters laid out will equal the multiplication of the two numbers. We split the array into four segments, as shown below:

We then calculate the number of counters in each segment, and add the results together, as follows: 20x40=800 20x2=40 3x40=120 3x2=6 TOTAL =966 We don’t need to draw out each of the counters but can just use rectangles as shown below:

The grid method is easier to understand than standard long multiplication, and so is taught first. When children are confident with with this method and understand fully the concept of units, tens and hundreds etc (number place value), then they can move onto the method that you were probably taught at school, long multiplication. Long Multiplication We will illustrate the method using the same calculation as before, 23 x 42. The method uses the principle that 23 x 42 is the same as 23 x (40 + 2) and get the answer by multiplying 2 x 23 and then 40 x 23 and adding the two results as follows: 23 x 42 __ 46 ( = 2 x 23) 920 (= 40 x 23) _____ TOTAL 966