@robertkaplinsky @pustam_egr @christianp @tao @marybourassa @mathequalslove @standupmaths @KarenCampe Hi friends and members of #mtbos and #iteachmath I need your help: I have a child and he needs to multiply. So in his school teachers teach him "multiply tables".
But I think in 21th century we could do better to memorize digit x digit tables.
Is there any method using only sums and counts and using ideally fingers to get without having to memorize?
You can justify using modulars forms of super-abstract-algebra if you want, but the problem is easy: find an east algorithm to get the multiplication of axb where a, b are interers < 9.
I did not find nothing more than:
- multiply by 9:
https://www.youtube.com/watch?v=wCpyag9XLgI
- multiply by numbers between 6 and 9
https://www.youtube.com/watch?v=xetE0IN-w3g but it requieres multiply by numbers less than 5.
- ypu can reduce to memorize all multiply tables to just where which gives us just 55 lines of memorization instead of 100.
But this are not ideal result.
I CC some university professors because perhaps you know some research about that rather than regular secondary or primary teachers.
Thanks in advance and sorry for disturb you.