When I printed out the form on yesterday’s post, it was missing the last two columns on the right, and since there was exactly room for them, I manually added them by ruler.  Then I filled out the multiplication table, by multiply  the number on the top by the number on the left, and writing the result in the box where the columns and rows intersect.

 The upper left quadrant is what my father had me fill out when I was six.  The upper right quadrant is less familiar territory, where I multiplied the larger numbers along the top by the smaller number on the left.  I did these in my head.  If it did not come easily, and I wasn’t sure I checked myself by calculator.  Write-overs mostly indicate that I had more difficulty performing that calculation in my head, and had to correct a number that I had written down.

The work fell into four quadrants:

Quadrant                                         Number of write-overs

1. Upper Left                                         0
2. Upper Right                                      9
3. Lower Left                                       14
4. Lower Right                                    30

This is a surprisingly good exercise to refresh one’s practice of multiplication.

Observations during this exercise:

In Quadrant 1, it came easier to multiply the larger number by the smaller number in reciprocal pairs.   For example it came easier to multiply 3 X 8 than 8 x 3, both of which are 24.   The order in which you multiply numbers does not change the outcome.  This is called the commutative law, and it applies to both addition and multiplication.

Quadrant 2 has the same multipliers as Quadrant 3,  only Quadrant 2 multiplies the larger number by the smaller number, and Quadrant 3 multiplies the smaller number by the larger number.  As you can see from the larger number of write-overs in Quadrant 3, 14 as opposed to nine in Quadrant 2, it was a little harder to multiply the smaller number by the larger one

Quadrant 4, with its 30 write-overs, multiplied two larger than accustomed numbers, and so it is not surprising that mental calculations were more than twice the other write-overs combined.

 My Lumosity performance results over time show that after a few months of steady improvement, I have more or less leveled off in over all, and I want to see if this multiplication practice will improve my performance in any of the categories, and permit renewed increasing Lumosity performance.