Now we multiply 29 by the main reference number, 10, to get 290. Then we multiply the numbers in
the top two circles (2 × 3) and add the result to 290.
Let’s try another one:
96 × 289 =
We choose 100 and 300 as our reference numbers. We set out the problem like this:
(100 × 3) 96 × 289 =
What do we write in the circles? Four and 11. Ninety-six is 4 below 100 and 289 is 11 below 300.Now multiply the 4 below 96 by the multiplication factor, 3. This gives us: 4 × 3 = 12. Draw another
circle below 96 and write 12 in this circle.
The calculation now looks like this:
Subtract 12 from 289.
289 − 12 = 277
Multiply 277 by the main reference number, 100.
277 × 100 = 27,700
Now multiply the numbers in the original circles (4 and 11).
4 × 11 = 44
Add 44 to 27,700 to get 27,744. This can easily be calculated in your head with just a little practice.
The full calculation looks like this:The calculation part of the problem is easy. The only difficulty you may have is remembering what
you have to do next.
If the numbers are above the reference numbers, we do the calculation as follows. We will take 12 ×
124 as an example:
(10 × 12) 12 × 124 =
We choose 10 and 120 as reference numbers. Because the numbers we are multiplying are both above
the reference numbers we draw the circles above. How much above? Two and 4, so we write 2 and 4 in