When I add:

036530234502744800 +

071896180211344400

Excel reports a value of:

108426414714089000

As can very easily be seen, manually adding the first three digits DOES NOT match the answer reported by Excel. I've also detected the same problem when using the Windows Calculator. And then I went online to a few sites and discovered that they too report errors when dealing with numbers of this magnitude.

In fact, take a look at the following addition as shown by Excel:

00000000000000001

00000000000002816

00000000001638400

00000000050331648

00000060129542144

00219902325555200

36310271995674600

-----------------------

36530234502744800

Simply manually adding THE FIRST COLUMN DIGITS (which yields a value of 19) does not correspond to the result as it should be! What gives? Would this have to do with internal floating point operations?