diff --git a/JiSuan.java b/JiSuan.java
new file mode 100644
index 0000000000000000000000000000000000000000..a936eb41dd7e6c3d0bde7048d6683850ce938c1e
--- /dev/null
+++ b/JiSuan.java
@@ -0,0 +1,124 @@
+package java2020spring;
+public class JiSuan {
+ private boolean isSecondNum = false;
+ String lastOp;
+ String firstNum = "0";
+ String secondNum = "null";
+ double store;
+String numString = "0123456789.";
+String opString = "+-*/";
+ 
+ public String catNum(String cmd, String text) {
+  String result = cmd;
+  if (!"0".equals(text)) {
+   if (isSecondNum) {
+    isSecondNum = false;
+   } else {
+    result = text + cmd;
+   }
+  }
+  if (result.indexOf(".") == 0) {
+   result = "0" + result;
+  }
+  return result;
+ }
+ public String setOp(String cmd, String text) {
+  this.lastOp = cmd;
+  this.firstNum = text;
+  this.secondNum = null;
+  this.isSecondNum = true;
+  return null;
+ }
+ public String cal(String text, boolean isPercent) {
+	  double secondResult = secondNum == null ? Double.valueOf(text)
+    .doubleValue() : Double.valueOf(secondNum).doubleValue();
+  if(secondResult == 0 && this.lastOp.equals("/")){
+   return "0";
+  }
+  if(isPercent){
+   secondResult = Mymath.multiply(Double.valueOf(firstNum), Mymath.divide(secondResult, 100));
+  }
+  if(this.lastOp.equals("+")){
+   firstNum = String.valueOf(Mymath.add(Double.valueOf(firstNum),secondResult));
+  }else if (this.lastOp.equals("-")) {
+   firstNum = String.valueOf(Mymath.subtract(Double.valueOf(firstNum),secondResult));
+  }else if (this.lastOp.equals("*")) {
+   firstNum = String.valueOf(Mymath.multiply(Double.valueOf(firstNum),secondResult));
+  }else if (this.lastOp.equals("/")) {
+   firstNum = String.valueOf(Mymath.divide(Double.valueOf(firstNum),secondResult));
+  }
+  this.isSecondNum = true;
+  return firstNum;
+ }
+ public String sqrt(String text){
+  this.isSecondNum = true;
+  return String.valueOf(Math.sqrt(Double.valueOf(text)));
+ }
+ public String setReciprocal(String text){
+  if (text.equals("0")){
+   return text;
+  }else{
+   this.isSecondNum = true;
+   return String.valueOf(Mymath.divide(1, Double.valueOf(text)));
+  }
+ }
+ public String mCmd(String cmd,String text){
+  if(cmd.equals("M+")){
+   store = Mymath.add(store, Double.valueOf(text));
+  }else if (cmd.equals("MC")) {
+   store = 0;
+  }else if (cmd.equals("MR")) {
+   isSecondNum = true;
+   return String.valueOf(store);
+  }else if (cmd.equals("MS")) {
+   store = Double.valueOf(text).doubleValue();
+  }
+  return null;
+ }
+ 
+ public String backSpace(String text){
+  return text.equals("0") || text.equals("") ? "0" :text.substring(0,text.length()-1);
+ }
+ 
+ public String setNegative(String text){
+  if(text.indexOf("-") == 0){
+   return text.substring(1,text.length());
+  }else{
+   return "-" + text;
+  }
+ }
+ public String clearAll(){
+  this.firstNum = "0";
+  this.secondNum = null;
+  return this.firstNum;
+ }
+ public String clear(String text){
+  return "0";
+ }
+ 
+ public String callMethod(String cmd, String text){
+  if(cmd.equals("C")){
+   return clearAll();
+  }else if(cmd.equals("CE")){
+   return clear(text);
+  }else if (cmd.equals("Back")) {
+   return backSpace(text);
+  }else if (numString.indexOf(cmd) != -1) {
+   return catNum(cmd, text);
+  }else if (opString.indexOf(cmd) != -1) {
+   return setOp(cmd, text);
+  }else if (cmd.equals("+/-")) {
+   return setNegative(text); 
+  }else if(cmd.equals("1/x")){
+   return setReciprocal(text);
+  }else if (cmd.equals("sqrt")) {
+   return sqrt(text);
+  }else if(cmd.equals("%")){
+   return cal(text, true);
+  }else if(cmd.equals("=")){
+   return cal(text, false);
+  }else {
+   return mCmd(cmd, text);
+  }
+ }
+}
\ No newline at end of file
diff --git a/JiSuanQi.java b/JiSuanQi.java
new file mode 100644
index 0000000000000000000000000000000000000000..a10b16b50e528eb3f90e2dbb2fe2ee06ec26afdb
--- /dev/null
+++ b/JiSuanQi.java
@@ -0,0 +1,129 @@
+package java2020spring;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.util.Arrays;
+import javax.swing.JButton;
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+public class JiSuanQi extends JFrame {
+ int PRE_WIDTH = 700;
+ int PRE_HEIGHT = 600;
+  JTextField text = null;
+ JButton button = null; 
+ String[] 按键1 = {"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};
+ String[] 按键2 = {"MC","MR","MS","M+"};
+ String[] 按键3 = {"Back","CE","C"};
+ JiSuan service = new JiSuan();
+ public JiSuanQi(){
+ this.setTitle("计算器");
+ this.setSize(PRE_WIDTH, PRE_HEIGHT);
+ this.setLocationRelativeTo(null);
+ this.setResizable(false);
+ JPanel panel = new JPanel();
+ panel.setLayout(new BorderLayout(10,1));
+ panel.add(getTextField(), BorderLayout.NORTH);
+ panel.setPreferredSize(new Dimension(PRE_WIDTH, PRE_HEIGHT));
+ JButton[] mButton = getMButton();
+ JPanel panel1 = new JPanel();
+ panel1.setLayout(new GridLayout(5,1,0,5));
+ for(JButton b : mButton ){
+   panel1.add(b);
+  }
+  panel.add(panel1,BorderLayout.WEST);
+  JButton[] rButton = getRButton();
+  JPanel panel2 = new JPanel();
+  panel2.setLayout(new BorderLayout(1,5));
+  JPanel panel21 = new JPanel();
+  panel21.setLayout(new GridLayout(1,3,3,3));
+  for(JButton b : rButton){
+   panel21.add(b);
+  }
+  panel2.add(panel21,BorderLayout.NORTH);
+  JButton[] nButton = getNButton();
+  JPanel panel22 = new JPanel();
+  panel22.setLayout(new GridLayout(4,5,3,5));
+  for(JButton b : nButton){
+   panel22.add(b);
+  }
+  panel2.add(panel22,BorderLayout.CENTER);
+  panel.add(panel2,BorderLayout.CENTER);
+  this.add(panel);
+  this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+  this.setVisible(true);
+ }
+JTextField getTextField(){
+  text = new JTextField("0",10);
+  return text;
+ }
+ JButton[] getNButton(){
+  String[] redButton = {"/","*","-","+","="};
+  JButton[] nbutton = new JButton[按键1.length];
+  for(int i = 0; i < this.按键1.length; i++){
+   JButton b = new JButton(this.按键1[i]);
+   b.addActionListener(getActionListener());  
+   Arrays.sort(redButton);
+   if(Arrays.binarySearch(redButton, 按键1[i]) >= 0){
+    b.setForeground(Color.black);
+   }else{
+    b.setForeground(Color.black);
+  }
+  nbutton[i] = b;
+  }
+  return nbutton;
+ }
+JButton[] getMButton(){
+  JButton[] mbutton = new JButton[按键2.length + 1];
+  mbutton[0] = getButton();
+  for(int i = 0; i < this.按键2.length; i++){
+   JButton b = new JButton(this.按键2[i]);
+   b.addActionListener(getActionListener());
+   b.setForeground(Color.black);
+   mbutton[i+1] = b;
+  }
+  return mbutton;
+ }
+ JButton[] getRButton(){
+  JButton[] rbutton = new JButton[按键3.length];
+  for(int i = 0; i < this.按键3.length; i++){
+   JButton b = new JButton(this.按键3[i]);
+   b.addActionListener(getActionListener());
+   b.setForeground(Color.black);
+   rbutton[i] = b;
+  }
+  return rbutton;
+ }
+ JButton getButton(){
+  button = new JButton();
+  return button;
+ }
+ ActionListener getActionListener(){
+  ActionListener actionListener = new ActionListener() {
+   public void actionPerformed(ActionEvent e) {
+    String cmd = e.getActionCommand();
+    String result = null;
+    try {
+     result = service.callMethod(cmd, text.getText());
+    } catch (Exception e2) {
+     System.out.println(e2.getMessage());
+    }
+    if(cmd.indexOf("MC") == 0){
+     button.setText("");
+    }else if(cmd.indexOf("M") == 0){
+     button.setText("M");
+    }
+    if(result != null){
+     text.setText(result);
+    }  
+   }
+  }; 
+  return actionListener;
+ }
+ public static void main(String[] args) {
+  new JiSuanQi();
+ }
+}
\ No newline at end of file
diff --git a/Mymath.java b/Mymath.java
new file mode 100644
index 0000000000000000000000000000000000000000..93580de2991d9a26646c4603984f99a06f2d4f25
--- /dev/null
+++ b/Mymath.java
@@ -0,0 +1,27 @@
+package java2020spring;
+import java.math.BigDecimal;
+public class Mymath {
+static BigDecimal getBigDecimal(double number){
+ return new BigDecimal(number);
+ }
+ public static double add(double num1, double num2) {
+  BigDecimal first = getBigDecimal(num1);
+  BigDecimal second = getBigDecimal(num2);
+  return first.add(second).doubleValue();
+}
+ public static double subtract(double num1, double num2) {
+  BigDecimal first = getBigDecimal(num1);
+  BigDecimal second = getBigDecimal(num2);
+  return first.subtract(second).doubleValue();
+} 
+ public static double multiply(double num1, double num2) {
+ BigDecimal first = getBigDecimal(num1);
+ BigDecimal second = getBigDecimal(num2);
+  return first.multiply(second).doubleValue();
+} 
+ public static double divide(double num1, double num2) {
+  BigDecimal first = getBigDecimal(num1);
+  BigDecimal second = getBigDecimal(num2);
+  return 0;
+}
+}
\ No newline at end of file
diff --git a/src/java2020spring/Test.java b/src/java2020spring/Test.java
deleted file mode 100644
index fc09c195f566d0e707f5e8a2f05fd168069c73a7..0000000000000000000000000000000000000000
--- a/src/java2020spring/Test.java
+++ /dev/null
@@ -1,10 +0,0 @@
-package java2020spring;
-
-public class Test {
-
-	public static void main(String[] args) {
-		System.out.println("Hello world!");
-
-	}
-
-}