diff --git a/program-14/program.c.c b/program-14/program.c
similarity index 100%
rename from program-14/program.c.c
rename to program-14/program.c
diff --git a/program-15/a.out b/program-15/a.out
new file mode 100755
index 00000000..e9bd45dd
Binary files /dev/null and b/program-15/a.out differ
diff --git a/program-15/program.c b/program-15/program.c
new file mode 100644
index 00000000..a263403b
--- /dev/null
+++ b/program-15/program.c
@@ -0,0 +1,13 @@
+#include<stdio.h>
+int main()
+{
+    int a,b,r=0,i;
+    printf("enter the range\n");
+    scanf("%d%d",&a,&b);
+    for(i=a;i<=b;i++)
+    {
+        if(i%3==0) r=r+i;
+    }
+printf("sum=%d\n",r);
+return 0;
+}
\ No newline at end of file
diff --git a/program-15/readme.md b/program-15/readme.md
new file mode 100644
index 00000000..59501430
--- /dev/null
+++ b/program-15/readme.md
@@ -0,0 +1,2 @@
+# Program-15
+## This is a c program to find sum of number which are divisible by 3
\ No newline at end of file
diff --git a/program-16/.vscode/launch.json b/program-16/.vscode/launch.json
new file mode 100644
index 00000000..c3a20dda
--- /dev/null
+++ b/program-16/.vscode/launch.json
@@ -0,0 +1,45 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        
+        { 
+            "name": "(gdb) Attach",
+            "type": "cppdbg",
+            "request": "attach",
+            "program": "enter program name, for example ${workspaceFolder}/a.out",
+            "processId": "${command:pickProcess}",
+            "MIMode": "gdb",
+            "setupCommands": [
+                {
+                    "description": "Enable pretty-printing for gdb",
+                    "text": "-enable-pretty-printing",
+                    "ignoreFailures": true
+                }
+            ]
+        },
+        {
+            "name": "gcc build and debug active file",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "${fileDirname}/${fileBasenameNoExtension}",
+            "args": [],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "externalConsole": false,
+            "MIMode": "gdb",
+            "setupCommands": [
+                {
+                    "description": "Enable pretty-printing for gdb",
+                    "text": "-enable-pretty-printing",
+                    "ignoreFailures": true
+                }
+            ],
+            "preLaunchTask": "gcc build active file",
+            "miDebuggerPath": "/usr/bin/gdb"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/program-16/a.out b/program-16/a.out
new file mode 100755
index 00000000..d58aae3f
Binary files /dev/null and b/program-16/a.out differ
diff --git a/program-16/program.c b/program-16/program.c
new file mode 100644
index 00000000..c773ea28
--- /dev/null
+++ b/program-16/program.c
@@ -0,0 +1,17 @@
+#include<stdio.h>
+int main()
+{
+    int n,s,sum=0,r;
+    printf("enter the number\n");
+    scanf("%d",&n);
+    s=n*n;
+    while(s!=0)
+    {
+        r=s%10;
+        sum+=r;
+        s/=10;
+    }
+    if(n==sum) printf("Neon number\n");
+    else printf("not neon number");
+    return 0;
+}
\ No newline at end of file
diff --git a/program-16/readme.md b/program-16/readme.md
new file mode 100644
index 00000000..12b396a0
--- /dev/null
+++ b/program-16/readme.md
@@ -0,0 +1,2 @@
+# Program-16
+## This is a c program to check given number is neon number
\ No newline at end of file
diff --git a/program-17/a.out b/program-17/a.out
new file mode 100755
index 00000000..7d2df0d4
Binary files /dev/null and b/program-17/a.out differ
diff --git a/program-17/program.c b/program-17/program.c
new file mode 100644
index 00000000..0d630efd
--- /dev/null
+++ b/program-17/program.c
@@ -0,0 +1,14 @@
+#include<stdio.h>
+int main()
+{
+    int n,s,i;
+    printf("enter the number\n");
+    scanf("%d",&n);
+    for(i=1;i<(n/2)+1;i++)
+    {
+        if(n%i==0) s+=i;
+    }
+    if(n==s) printf("perfect number\n");
+    else printf("non-perfect number\n");
+    return 0;
+}
\ No newline at end of file
diff --git a/program-18/a.out b/program-18/a.out
new file mode 100755
index 00000000..0c9fa121
Binary files /dev/null and b/program-18/a.out differ
diff --git a/program-18/program.c b/program-18/program.c
new file mode 100644
index 00000000..45e5f37b
--- /dev/null
+++ b/program-18/program.c
@@ -0,0 +1,29 @@
+#include<stdio.h>
+int power(int x,int y)
+{ int i,t=x;
+    for(i=1;i<y;i++) x*=t;
+    return x;
+}
+int main()
+{
+    int t,n,s,i,count=0,r,sum=0;
+    printf("enter the number\n");
+    scanf("%d",&n);
+    t=s=n;
+    while(s!=0)
+    {
+        s=n/10;
+        count++;
+        
+    }
+    printf("%d\n",count);
+        while(n!=0)
+    {
+        r=n%10;
+        sum+=power(r,count);
+        n/=10;
+    }
+     if(sum==t) printf("Amstrong number = %d\n",sum);
+    
+    return 0;
+}
\ No newline at end of file
diff --git a/program-19/a.out b/program-19/a.out
new file mode 100755
index 00000000..2844dfd8
Binary files /dev/null and b/program-19/a.out differ
diff --git a/program-19/program.c b/program-19/program.c
new file mode 100644
index 00000000..7851ddcd
--- /dev/null
+++ b/program-19/program.c
@@ -0,0 +1,11 @@
+#include<stdio.h>
+int main()
+{ 
+    int i,x,y,t;
+printf("enter x and y\n");
+scanf("%d%d",&x,&y);
+t=x;
+    for(i=1;i<y;i++) x*=t;
+    printf("power =%d\n",x);
+    return 0;
+}
\ No newline at end of file
diff --git a/program-20/a.out b/program-20/a.out
new file mode 100755
index 00000000..5d53f3ee
Binary files /dev/null and b/program-20/a.out differ
diff --git a/program-20/program.c b/program-20/program.c
new file mode 100644
index 00000000..bfe8670d
--- /dev/null
+++ b/program-20/program.c
@@ -0,0 +1,8 @@
+#include<stdio.h>
+void main()
+{
+if(printf("hello world\n"))
+{
+
+}
+}
diff --git a/program-21/a.out b/program-21/a.out
new file mode 100755
index 00000000..241d921c
Binary files /dev/null and b/program-21/a.out differ
diff --git a/program-21/program.c b/program-21/program.c
new file mode 100644
index 00000000..0cfb05d1
--- /dev/null
+++ b/program-21/program.c
@@ -0,0 +1,17 @@
+#include<stdio.h>
+int main()
+{
+    int a,i,count=0;
+    printf("enter the number\n");
+    scanf("%d",&a);
+    for(i=2;i<=a/2;i++)
+    {
+        if(a%i==0)
+        { 
+            count=1;
+        break;
+    }}
+if(count) printf("not prime");
+else printf("prime");
+return 0;
+}
\ No newline at end of file