Adding Large Numbers on Calculators

Date: 6/27/96 at 22:3:45
From: Anonymous
Subject: Large Numbers on Calculators

Dear Doctor Math,

If a number is too large to fit on a calculator screen, how do you 
do addition? These aren't decimal numbers that can be rounded.

Eloise Fartdon, year 6

Date: 6/28/96 at 8:38:57
From: Doctor Peter
Subject: Re: Large Numbers on Calculators

I would split up the numbers into two parts.  For example, if I wanted
to add 123,456,789,543 to 23,765,234,987, I would break each number
into two parts, the billions and millions, and the thousands and 
ones.   Then you could have 123,456,000,000 + 23,765,000,000 (added
without the 0's and put back on afterwards) and add that to
789,543 + 234,987.  Be sure to do the last addition on paper, because
you might need to carry something over from one half to the other.
If all you need to do is add two or three numbers, it might just be
a little easier to do it the 'old-fashioned' way, with a pencil.

- Doctor Peter, The Math Forum
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