Double and Half Method

Double and Half Method

        The double and half method is used to make two numbers easier to multiply. The idea is you can double one number and half the other before multiplying.

         1)  35 x 24 =    35 x 2  x  24 ÷ 2   =   70 x 12 = 840.

Here 24 is divided by 2 and multiple that 2 with 35  to  make the figures easy to multiple orally

                The answer is 840.

         2)  57 x 22 =   57 x 2  x  22 ÷ 2  = 114 x 11 = 1254.

                The answer is 1254.

Here  22 is divided by 2 and  multiple that 2 with 57  to  make the figures easy to multiple orally

       3)   6 ¹/₄ x 96 =

         Multiply and Divide by 4.

          6 ¹/₄ x 4 x  96 ÷ 4  =  25 x 24 = 600.

        The answer is 600.

         4)   66 x 21 =

       Multiply and Divide by 6.

        66 ÷ 6  x  21 x 6 =  126 x 11 = 1386.

      The answer is 1386.