Not able to compare varchar filed with number

Question

tag3 is varchar filed can have number data
Below works good
comparison with 0 or 1 works also less than or equal operator works
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)<=24
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=0
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=1
>
greater or equal comparison doesn't work
doesn't work
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)>=24
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=2
any number beyond 1 doesn't work
Error :ORA-01722: invalid number
01722. 00000 - "invalid number"
*Cause:   
*Action:
Not able to understand the logic of comparing the number with
same is tried with TO_NUMBER as well
works good
select I.* from ob_release_instruction I where to_number(i.tag3) > 0
Not working ( changed the value to more than 0)
select I.* from ob_release_instruction I where to_number(i.tag3) > to_number('24')
Not working
select I.* from ob_release_instruction I where to_number(i.tag3) > 24
Above two query is not working throwing below error
ORA-01722: invalid number
01722. 00000 - "invalid number"
*Cause:   
*Action:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Answer 1

Here is the sample
tag3 is varchar filed can have number data
TAG3 VARCHAR2(30 CHAR)
column has few nulll, alpha numeric and number values
I want to check entered number is greater than 24 or not
Below works good
comparison with 0 or 1 works also less than or equal operator works
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)<=24
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=0
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=1
greater or equal comparison doesn't work
doesn't work
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)>=24
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)=2
select TAG3 from ob_release_instruction i WHERE CAST(i.tag3 as NUMBER)>2
any number beyond 1 doesn't work
Error :ORA-01722: invalid number
01722. 00000 - "invalid number"
*Cause:
*Action:
Not able to understand the logic of comparing the number with
same is tried with TO_NUMBER as well
works good
select I.* from ob_release_instruction I where to_number(i.tag3) > 0
Not working ( changed the value to more than 0)
select I.* from ob_release_instruction I where to_number(i.tag3) > to_number('24')
Not working
select I.* from ob_release_instruction I where to_number(i.tag3) > 24
Above two query is not working throwing below error
ORA-01722: invalid number
01722. 00000 - "invalid number"
*Cause:
*Action: