Zero in front of decimal point is missing

I have a procedure to display redeem unit when user key in at front end.Currently, the data type I used is NUMBER, however when the redeem unit is less than 1, then the zero in front of decimal point is missing. For example, 0.6767 become .6767

I try to format it with to_char(redeem_units,‘0.9999’), but seem like it still cant display the leading zero.

Should I use other data format or any other better alternatives?