If you want to apply conditional validation on 'Second Number' or 'Third Number', then you need to add 'First Number' input as '25'
{{userFormGroup.controls.firstNumber.errors.factor.message}}
To apply the validation of factor on 'Fifth Number' field
{{userFormGroup.controls.fifthNumber.errors.factor.message}}
To apply the validation of factor on 'Fourth Number' field, then enter the value '25' in 'First Number' textbox
Conditional Expression with type 'string'
{{userFormGroup.controls.thirdNumber.errors.factor.message}}
you can enter only factors of 50
Shows custom message.
{{userFormGroup.controls.fourthNumber.errors.factor.message}}
you can enter only factors of 50
Shows custom message.
{{userFormGroup.controls.sixthNumber.errors.factor.message}}