Numbers Above the Reference Number 23
Th e numbers in the circles above are plus numbers and
the numbers in the circles below are minus numbers.
Let’s try another one. How about 12 × 17?
Th e numbers are above 10, so we draw the circles above. How much
above 10? Two and 7, so we write 2 and 7 in the circles.
+2
+7
10 12 × 17 =
What do we do now? Because the circles are above, the numbers are
plus numbers, so we add crossways. We can either do 12 plus 7 or
17 plus 2. Let’s do 17 plus 2.
17 + 2 = 19
We now multiply 19 by 10 (our reference number) to get 190 (we
just put a 0 after the 19). Our work now looks like this:
+2
+7
10 12 × 17 = 190
Now we multiply the numbers in the circles.
2 × 7 = 14
Add 14 to 190 and we have our answer. Fourteen is 10 plus 4. We
can add the 10 fi rst (190 + 10 = 200), then the 4, to get 204.
Here is the fi nished problem:
+2
+7
10 12 × 17 = 190
- 14
204 Answer