InputField Button didn't work on method

I'm currently writing a code where the player has to confirm their answer by hitting a button. Once they hit a button, a score is added. However, when I tried to script the code, the button didn't work even if I already added the script into the button. Can anyone help me to check and see if the script is right?

 using UnityEngine.UI; //Tell Unity that we're going to use UI (InputField, Button, Etc)
 
 public class UIInputField : MonoBehaviour {
 
 //This program allowed the player to type the answer and pressed the button for confirmation. 
     
     public Text numberText; //reference for the number text
 
     public Text placeholderText; //reference for the placeholder text
     public GUIText scoreText; //reference for the score GUI text
 
     public int score; //reference the game score, always be a whole number
 
     // Use this for initialization
     void Start () 
     {
         score = 0; //sets the score to zero
         UpdateScore (); //set the score to the starting value
 
         //First, I use this text to refer to the game object, which is the "NumberText", and place a text component on it. 
         numberText = GameObject.Find("NumberText").GetComponent<Text>(); //() = call on gameobject image
         //reference to the game component
 
         placeholderText = GameObject.Find("Placeholder").GetComponent<Text>();
     
     }
 
     public void AddScore(int newScoreValue)
     {
         score += newScoreValue;
         UpdateScore();
     }
 
     void UpdateScore()
     {
         scoreText.text = "" + score;
     }
 
     public void NumberField (string inputFieldString) //Stores the text that was typed in. 
     {
         numberText.text = inputFieldString; //The text is equal to the text that was typed in,  and calls the text to be displayed in the game.
     }
 
     public void ConfirmAnswer()
     {
         if (placeholderText.enabled == true) 
         { 
             Debug.Log ("Please Enter the Answer");
             AddScore (score); //a score is added whenever the player enters the button
         } 
         else 
         {
             Debug.Log ("Confirm Answer");
         }
     }
     
 }