Typing ALT + 251 and ALT + 0251 at the keyboard produce different character entries

In Windows:

• when I press Alt + 251, I get a √ character


• when I press Alt + 0251 get û character!

A leading zero doesn't have value.

Actually, I want get check mark(√) from Chr(251) function in Client Report Definition (RDLC) but it gets me û!

I think it interprets four numbers as hex not decimal.