A Conversation for Integers and Natural Numbers
Nine
tayporttony Started conversation Jul 27, 2009
Many years ago, I recall seeing proofs of the two following theories:
a) That any transposition error e.g. 54-45, will always be a multiple of 9
b) That the sum of the digits of any multiple of 9 will always itself be a multiple of 9 e.g. 9*24=216. 2+1+6=9
Does anyone know where I could find these proofs please?
Key: Complain about this post
Nine
More Conversations for Integers and Natural Numbers
Write an Entry
"The Hitchhiker's Guide to the Galaxy is a wholly remarkable book. It has been compiled and recompiled many times and under many different editorships. It contains contributions from countless numbers of travellers and researchers."