median
don steward
mathematics teaching 10 ~ 16

Monday, 3 December 2007

loooooong multiplication - grid method

the Gelosia or lattice method for long multiplication was a method seemingly in common use centuries ago

it can be a helpful method for some students

using 37 multiplied by a two digit multiple of 3 (not bigger than 27) provides some easy to check answers
e.g. 37 x 15 ,  24 x 37 ,  37 x 27

the method was used historically in Europe (by their great, great ancestors)

a picture, from Italy, of a long multiplication sum - supposedly from 1478 (in the Treviso arithmetic):



the sum is 934  x  314

a problem from over 500 years ago













an older manuscript from 1300:

 the sum is
4 569 202 x
502 403















with an answer of 2,295,570,802,406


No comments: