>>Once the data is translated to the final resting place in decimals of a foot the coordinates are 1044943.91129001,173435.132338795,0 in engineering units. I then have to scale this engineering data up by 12, change the units and move the data to1044943'-10.935480132",17345'-1.58806554",0.0000. After I move the data to these coords and list the result I get X = 1.2539E+07 Y = 17345'-1 9/16" Z = 0'-0" The x is in inches and the y is in FTIN.

>>Can anyone explain what is going on here?

What is it that you need explaining? You seem to have a pretty good handle on what your 'challenges' are. If you're familiar with floating point, then you understand what "1.2539E+07" is? If not, that is a rounded off version of the correct X Position - (1044943.91129001 * 12 = 12539326.93548012), which is 1.2539, with your decimal point shifted "E+" 7 digits to the left.

You're probably already seeing round off errors. Since you are stuck with a fixed amount of numeric characters to represent your locations, I would limit the back and forth between converting units. Every time you divide by 12, you are looking at the possibility of adding at LEAST another number to the RIGHT of the decimal point; and every time you multiply by 12, you are adding a character to the LEFT of the decimal point, which means knocking another one off from the right....

For utmost precision, Id start off by converting everything to one type of unit. Id probably Multiply the smaller units, rather than divide the larger ones; you'll only add a single character to the left that way, but dividing can add mucho decimals to the right....

And I'd do all my transations last.