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 (i.e. by their great, great ancestors)
two pictures from Italy of long multiplication sums, supposedly from 1478 CE
in the Treviso arithmetic:
(a problem from over 540 years ago)
56789 x 1234
from an older manuscript, around 1300 CE:
the sum is
4 569 202 x 502 403
with an answer of 2,295,570,802,406
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