I am currious to find an explanation for this. In excel I created a
simple formula to calculate 12 to the 19th power written in full
numerical form. At 12 to the 17th excel makes an error (note the
zero's). Try it yourself. Anyone know why this happens?

12
144.00
1728.00
20736.00
248832.00
2985984.00
35831808.00
429981696.00
5159780352.00
61917364224.00
743008370688.00
8916100448256.00
106993205379072.00
1283918464548860.00 <-- here is where the error starts, the number
should end with 864.00
15407021574586400.00
184884258895036000.00
2218611106740440000.00
26623333280885200000.00
319479999370623000000.00

Try this with any really large number. The calculations drop off at the
17th digit. I've tried this on different computers all with the same
result.