diff --git a/2209040021/chaoter_1.3 b/2209040021/chaoter_1.3
new file mode 100644
index 0000000000000000000000000000000000000000..f70ea4ab18ec3b99d8af5fe5f24daf26148b9f40
--- /dev/null
+++ b/2209040021/chaoter_1.3
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <math.h>
+void main(){
+    int m; 
+    int i;  
+    int k;   
+    printf("输入一个整数：");
+    scanf("%d",&m);
+    k=(int)sqrt( (double)m );
+    for(i=1;i<=k;i++)
+        if(m%i==0)
+            break;
+    if(i>k)
+        printf("%d是素数。\n",m);
+    else
+        printf("%d不是素数。\n",m);
+ 
+    return 0;
+}
\ No newline at end of file