Last two digits changed when converting character value into numeric value

[cindyforest7]

I have a character variable with values of numbers (17-18 digits). I wanted to convert them into numeric. But the last two digits have changed for some reason.

The sas code I used is:

data convert;

set original;

numeric=input(character 18.0);

format numeric 18.0;

run;

[pradeepalankar]

can't use more then 16 digits. refer this: http://support.sas.com/techsup/technote/ts654.pdf

[snoopy369]

Even 16 digits is not safe.  2^53 (around 4x10^15) is the maximum storable number with full precision; so some Visa numbers may be storable, but no Mastercard numbers (5x10^15).  This of course is often relevant with credit card numbers simply because they are right at that point of precision loss.

[snoopy369 · Accepted solution]

Depending on your operating system, SAS can only handle around 15 digits of precision with a numeric (in Windows, out of 64 bits for an 8 byte number, 1 is the sign and 11 are the exponent, meaning 52 bits are available for the mantissa (the precise digits) - around 4x10^15. Any number over 4x10^15 will begin losing precision.  See SAS(R) 9.2 Language Reference: Concepts, Second Edition for more information.