boopathi wrote...
....
If I enter =TEXT(0.000000006036,"0.000e-9"), it gives "#VALUE!"

But if I use =TEXT(0.000000006036,"0.000E-9") it gives correct value as
6.036E-9.

I guess 'e' was not handled properly.
....

It may not be well documented, but Excel only accepts upper case E to
denote the exponential components in scientific number formats even
though it accepts upper and lower case E/e when entering numbers using
scientific notation.