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Posts tagged with speed mathematics

Multiply the Japanese Way

June5

Using diagonals lines (from left to right for each number) we can solve longer multiplication problems quite easily. Simply draw the intersections, find the groups, and then count off the points. Well, it is a little more involved for those bigger multiples: See how here:

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Fast Squaring – this is cool and will impress your friends!

December14

If we need to find the square of a number that ends in a “5”, such as 75, we can use this fast system to impress our friends (or ourselves!) Step 1: If the last digit is 5, then the square of those numbers always ends with 25. So the last two digits of 75 […]

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Amazing Brain Man

October9

Daniel Tammet was bullied at school and also suffers from autism, etc. Yet, he has been gifted with an amazing ability to manipulate numbers. Check out this video link for an insight into Daniel’s rather different way of thinking mathematically.

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Speed Mathematics – from the horrors of a Concentration Camp

August28

Can you multiply 5132437201 by 452736502785 in seventy seconds without using a calculator? A Russian Jew, Jakow Trachtenberg, developed his system of “speed mathematics” while he was in Hitler’s concentration camps as a political prisoner during World War II. Read more about this amazing Mathematician here. You can download a copy of his work at this […]

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Post Support

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]