regex code assistance for entering 600 in a input field

Hello I was trying to understand how to work with a regex expression forwhen a User enters starts typing in600in the input field, then populate the error message. What would be the regex code for that?
Currently I have `^[\w'\-,.][^0-9_!¡?÷?¿\/\\+=@#$%ˆ&*(){}|~<>;:[\]]{2,}$`