Decimal Field Display Pattern

Hi,

I have a Decimal Field whose Interger length is 23 and Decimal Length 2.
when i give some input it should not add zero before the Interger part.
I tried by giving a Display Pattern of the format
ZZZZZZZZZZZZZZZZZZZZZZ9.99.

Up to 16 digits(Interger part) the value is formated correctly.
when the length crosses 16 it is showing some other number

say for the input 1234567890123456 output is 1234567890123456.00
12345678901234567 output is 12345678901234566
for some other numers also it is displaying some other number.