Large numbers are showing as exponential in appian display.

HI Shweta, You can format this value using function text().

Is there any other way to keep it float value

The original value will remain unchanged as Float type.  The only thing that's changing is the text display value that Appian outputs by default.

I have used text function, But it's working only for 8 digits.

Either you keep it in float and live with the limit or you convert it into text using text() function and surpass the limit.