diff --git a/.classpath b/.classpath
new file mode 100644
index 0000000..038a0e7
--- /dev/null
+++ b/.classpath
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-13">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ae3c172
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/bin/
diff --git a/.project b/.project
new file mode 100644
index 0000000..a29c479
--- /dev/null
+++ b/.project
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>Educoder</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>
diff --git a/.settings/org.eclipse.jdt.core.prefs b/.settings/org.eclipse.jdt.core.prefs
new file mode 100644
index 0000000..ef28d2b
--- /dev/null
+++ b/.settings/org.eclipse.jdt.core.prefs
@@ -0,0 +1,14 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=13
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=13
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=13
diff --git a/src/小组协同/sizeyunsuan.java b/src/小组协同/sizeyunsuan.java
new file mode 100644
index 0000000..f980641
--- /dev/null
+++ b/src/小组协同/sizeyunsuan.java
@@ -0,0 +1,32 @@
+package С��Эͬ;
+
+public class sizeyunsuan {
+	public double add(double add1, double add2) {
+		//�ӷ�
+		double result;
+		result = add1 + add2;
+		return result;
+	}
+	
+	public double subtract(double sub1, double sub2) {
+		//����
+		double result;
+		result = sub1 - sub2;
+		return result;
+	}
+	
+	public double multiply(double mul1, double mul2) {
+		//�˷�
+		double result;
+		result = mul1 * mul2;
+		return result;
+	}
+	
+	public double divide(double div1, double div2) {
+		//����
+		double result;
+		result = div1 / div2;
+		return result;
+	}
+
+}