127-register-student.cls

public String registerStudent(String name, String phone, String email) {
    // Insert new Student record
    apxio__Student__c student = new apxio__Student__c();
    student.Name = name;
    student.apxio__Phone__c = phone;
    student.apxio__Email__c = email;
    insert student;
    
    // Get the autogenerated registration number of the new record
    apxio__Student__c createdStudent = [SELECT apxio__Registration_Number__c FROM apxio__Student__c WHERE Id = :student.Id];
    return createdStudent.apxio__Registration_Number__c;
}