3 ms·

Huh, I was never taught the chunck/grid system (39yr old US public school) but that is almost exactly how I taught myself in later years, (mid 20ies) to do mult

• blahedo 16y ago
  I had the same reaction: it's really remarkable how well those two methods map to my own mental arithmetic algorithms. The grid multiplication technique would also prepare the student pretty well for polynomial multiplication (which is how I originally derived it).
  • Natsu 16y ago
    Same here. I taught myself the same methods and several other similar things that I found uses for later, when I got my degree in mathematics.
• JunkDNA 16y ago
  Same reaction here. The grid method makes so much more intuitive sense to me than the way I was taught. I do it without even thinking about it sometimes.
• weavejester 16y ago
  I do pretty much the same thing. I was taught traditional long multiplication in school, but its a technique that is designed to be worked out with a pen and paper, and doesn't tell you a lot about why the technique works. The grid system seems more geared toward mental arithmetic and understanding, and allows one to easily approximate an answer, rather than working it out exactly. This is pretty much exactly what's required in the modern world, and that's probably why lots of people have discovered this technique independently.
• poutine 16y ago
  This is always how I've done multiplication in my head as well. Just seems natural and pretty easy to do up to 99x99, after which it's too annoying to track.