Introduced and added HCF.c, LCM.c and prime.c

C/HCF.c

@@ -0,0 +1,14 @@
+#include<stdio.h>
+int main(){
+    int a,b,i;
+    printf("Enter a");
+    scanf("%d", &a);
+    printf("Enter b");
+    scanf("%d", &b);
+    for(i=(a>b?b:a);i>1;i--){
+        if(a%i==0 && b%i==0){
+            printf("HCF is %d",i);
+            break;
+        }
+    }
+}

C/LCM.c

@@ -0,0 +1,14 @@
+#include<stdio.h>
+int main() {
+   int a, b,i;
+   printf("Enter a");
+   scanf("%d",&a);
+   printf("Enter b");
+   scanf("%d",&b);
+   for(i=(a>b?a:b);i<=(a*b);i=i+(a>b?a:b)){
+       if(i%a==0 && i%b==0){
+           break;
+       }
+   } 
+   printf("LCM is %d", i);
+}

C/prime.c

@@ -0,0 +1,19 @@
+#include<stdio.h>
+int main(){
+    int number,i,flag=0;
+    printf("Ener the number you want to check");
+    scanf("%d",&number);
+    for(i=2;i<number;i++){
+        if(number%i==0){
+            flag=1;            
+        }
+    }
+    if(flag!=1){
+        printf("%d is a prime number",number);
+    }
+    else
+    {
+        printf("Not a prime number");
+    }
+
+}

introduce-yourself/Jayant-saksham.md

@@ -0,0 +1,3 @@
+Hi there, my name is Jayant Saksham.
+I am a second year student at Delhi Technological University (DTU). I am a flutter developer and this is my first open source contribution.
+Hope to learn something new from here