Simple multiplication trick
Some education system teach children math skills by teaching them
how to do math. Some other education systems, ours included, starts by
forcing the kids to memorize lots of meaningless information that looks
like math, so that they will have the appearance of being able to do
basic math.
Such as the multiplication table. Instead of explaining to kids the
idea behind multiplying, they are forced to learn by rote the results
of multiplication of all pairs of single digit numbers.
I personally preferred to do the math. This meant that it usually took me a
bit longer than for some of my classmates to come up with the answer, but
it also meant I was never in a position where I couldn’t provide an
answer due to forgetting it…
In any case, here’s a simple trick that kids (can) use to aid in
this. It allows to get result for the whole multiplication table when
you only need to remember the lower half of it (1-5 times the rest):
Hold two fisted hands.
On each hand count off fingers by the
difference from the number and 5 (so it you multiply 6×7, count one
finger on one hand, and two fingers on the other).
Each finger that
you counted is worth 10 (in this example, that’s 2+1, so we have 30).
Now multiply the remaining fingers on each hand (4*3, after we used 1
and 2. So 12 here).
Add the two results. Presto! The
correct multiplication answer:
30+12 =42 = 7*6 .
Cute trick.
Of course, kids are mean towards anyone who is different, and so as
you may have noticed the trick only work if you have five fingers on
each hand. Those unfortunate souls scary freaks that have lost a finger, or the scary evil demon mutants with an extra finger, cannot use it as-is.
February 3rd, 2005 at 13:57 EET | Categories: Science |
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