Speed Math for Kids Achieve Their Full Potential

the circles.

Now we  multiply    the number  above   the 12  (2) by  the multiplication  factor, 12.

2   ×   12  =   24

Draw    another circle  above   the 12  and write   24  in  it.

Now we  add crossways.

124 ×   24  =   148

Write   148 after   the equals  sign    and multiply    it  by  our main    reference   number, 10.

148 ×   10  =   1,480

Now multiply    the numbers in  the original    circles,    2   ×   4,  and add the answer  to  the subtotal.

2   ×   4   =   8

1,480   +   8   =   1,488   Answer

The completed   problem looks   like    this:

I try to choose reference numbers that keep both numbers either above or below the reference
numbers, so that I have an addition rather than a subtraction at the end. For instance, if I had to multiply
9 times 83, I would choose 10 and 90 as reference numbers rather than 10 and 80. Although both would
work, I want to keep the calculations as simple as possible.
Let’s calculate the answer using both combinations, so you can see what happens.
Firstly, we will use 10 and 90.

That was straightforward. We multiplied 9 by 1 and wrote 9 in the bottom circle. Then we performed
the following calculations:

83  −   9   =   74