The issue of numeric precision affects the return values of almost all SAS math functions and many numeric values returned from SAS procedures. Numeric values in SAS for UNIX are represented as IEEE double-precision floating-point numbers. The decimal precision of a full 8-byte number is effectively 15 decimal digits.
|Length in Bytes||
When you are specifying variable lengths, keep in mind that the length of a variable affects both the amount of disk space used and the number of I/O operations required to read and write the data set. See SAS Language Reference: Dictionary for more information about specifying variable lengths.
Numeric dummy variables (variables whose only purpose is to hold 0 or 1) can be stored in a variable whose length is 3 bytes.
Fractional numbers lose precision if they are truncated. In addition, you must ensure that the values of your variable will always be represented exactly in the number of bytes that you specify. You can do this programmatically in a DATA step with the TRUNC function. No warnings or errors are issued when the length that you specify in the LENGTH statement results in the truncation of data.