diff --git a/credit.c b/credit.c
new file mode 100644
index 0000000..762c92b
--- /dev/null
+++ b/credit.c
@@ -0,0 +1,57 @@
+#include<stdio.h>
+#include<cs50.h>
+int main()
+{
+    long num = get_long("Enter num : ");//Enter number of card
+    int last, sec, count = 0, sum1 = 0, sum2 = 0, temp, sum = 0;
+    while (num > 0)//for enter number only
+    {
+        sec = last;
+        last = num % 10;//give last num of numbers 
+        count++;
+        if (count % 2 == 0)
+        {        
+            temp = last * 2 ;
+            if (temp >= 10)
+            {
+                sum1 += temp % 10;
+                sum1 += temp / 10;
+            } 
+            else
+            {
+                sum1 += temp;
+            }
+        }
+        else
+        {
+            sum2 += last;
+        }
+        num /= 10;
+    }
+    sum = sum1 + sum2;
+    if ((sum % 10) == 0)//check valid
+    {
+        if (((sec == 1 && last == 5) || (sec == 2 && last == 5) || (sec == 3 && last == 5) || (sec == 4 && last == 5) 
+             || (sec == 5 && last == 5)) && count == 16)
+            
+        {
+            printf("MASTERCARD\n");//check master card
+        }
+        else if (((sec == 4 && last == 3) || (sec == 7 && last == 3)) && count == 15)//check AMEX
+        {
+            printf("AMEX\n");
+        }
+        else if (last == 4 && (count == 13 || count == 16))//check VISA
+        {
+            printf("VISA\n");
+        }
+        else
+        {
+            printf("INVALID\n");
+        }
+    }
+    else 
+    {
+        printf("INVALID\n");
+    }
+}