You did not show us how the value is displayed (which function is used to print the value to a string or display). Depending on that you can define how floating point values are printed.
Most of these functions (besides C++ streams) use the printf
] formatting. For floating point values the 'f' format should do what you want. Your example output looks like the 'g' or 'e' format has been used.
To get more significand digits, specify also the precision.