SUGGESTION: Append 0 before the decimal if the input is only a decimal instead of returning NAN

[Hat52]

I have faced this issue where when the user inputs a decimal as the input the BigNumber returns NAN. What I suggest is instead of returning NaN we can append 0 before the decimal. This can be an optional feature.

For example: Input is equal to. Currently we return NaN. Suggestion is we should return 0.