Why Number fields keep removing the leading number zero?

[Xing]

I have a number field, no formula related, just simple number field. I have been trying to type 0210, it shows 210 instead, the leading "0" is automatically missing, is there anyway that I can keep the 0? thanks

[Sho]

Leading zeros are removed in number fields.
You may use the Single line text field.

Or use this formula to convert a number field.

REPT("0", 4-LEN({Number}&"")) & {Number}