diff --git a/DeitelC/Chapter3/IsPrime.c b/DeitelC/Chapter3/IsPrime.c
index f89f9ff..6fb9e58 100644
--- a/DeitelC/Chapter3/IsPrime.c
+++ b/DeitelC/Chapter3/IsPrime.c
@@ -6,20 +6,20 @@ int count = 0;
 
 while (a < number) {
 	if(number%a == 0) {
-	count += 1;
-	a++;
-    } else {
-        a++;
+        printf("%s\n", "No it isn't a Prime");
+	    return;
     }
+    a++;
 }
 
 if(count == 1) {
 	printf("%s\n", "Yes it's a Prime");
 
     } else {
-	printf("%s\n", "No it isn't a Prime");
+	
     }
 }
+
 int main(void) {
     int number;
     printf("%s\n", "Enter a integer!");
diff --git a/DeitelC/Chapter3/a.exe b/DeitelC/Chapter3/a.exe
deleted file mode 100644
index e4b3924..0000000
Binary files a/DeitelC/Chapter3/a.exe and /dev/null differ
diff --git a/DeitelC/Chapter4/1to20.c b/DeitelC/Chapter4/1to20.c
new file mode 100644
index 0000000..7489484
--- /dev/null
+++ b/DeitelC/Chapter4/1to20.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+int main(void){
+    int counter = 1;
+    while(counter<= 20) {
+        if(counter%5==0) {
+            printf("%d\t",counter);
+            counter++;
+        } else {
+            counter++;
+        }
+        }
+        printf("\n");
+        for(int x = 1; x<=20 ;++x) {
+            if (x%5==0) {
+                printf("%d\t", x);
+            } else {
+
+            }
+    }
+    return 0;
+}
\ No newline at end of file
diff --git a/DeitelC/Chapter4/CelciusToFahrenheit.c b/DeitelC/Chapter4/CelciusToFahrenheit.c
new file mode 100644
index 0000000..8fc14ea
--- /dev/null
+++ b/DeitelC/Chapter4/CelciusToFahrenheit.c
@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+int CelciusConvert(int c) {
+    int f;
+    f = ((c*9)/5)+32;
+return f;
+}
+
+int main(void) {
+    int c;
+    int f;
+    printf("%s\n", "Enter Celcius degree!");
+    scanf("%d", &c);
+    printf("%d %s %d",c, " Celcius equals to Fahrenheit: ", CelciusConvert(c));
+}
\ No newline at end of file
diff --git a/DeitelC/Chapter4/a.exe b/DeitelC/Chapter4/a.exe
index 9ef15aa..8c66b27 100644
Binary files a/DeitelC/Chapter4/a.exe and b/DeitelC/Chapter4/a.exe differ
diff --git a/DeitelC/Chapter4/check.c b/DeitelC/Chapter4/check.c
new file mode 100644
index 0000000..db8bfbc
--- /dev/null
+++ b/DeitelC/Chapter4/check.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+
+int main() {
+    int i = 5, j = 7, k = 4, m = -2;
+    //printf("%d", i >= 5 && j > 4);
+    /*printf("%d", !m && k > m);
+    printf("%d", !k || m); */
+    printf("%d", !2);
+}
\ No newline at end of file
diff --git a/DeitelC/Chapter4/test1.c b/DeitelC/Chapter4/test1.c
new file mode 100644
index 0000000..8153011
--- /dev/null
+++ b/DeitelC/Chapter4/test1.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+ int main() 
+ {
+ int x, i, j; 
+ // prompt user for input
+ printf("%s", "Enter an integer in the range 1-20:");
+ scanf("%d", &x); // read values for x
+ for (i = 1; i <= x; i++) { // count from 1 to x
+ for (j = 1; j <= x; j++) { // count from 1 to x
+ if (j==i) 
+ printf("%c",'@'); // output @
+ else
+ printf(" "); 
+ } // end inner for
+ printf("\n");
+ } // end outer for 
+ } // end of main
\ No newline at end of file
diff --git a/a.exe b/a.exe
new file mode 100644
index 0000000..eb05af6
Binary files /dev/null and b/a.exe differ
diff --git a/test1.c b/test1.c
new file mode 100644
index 0000000..6103fc6
--- /dev/null
+++ b/test1.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+
+int main(void){
+
+int num;
+int e = 1;
+int decimal = 0;
+
+printf("%s\n", "Enter UNSIGNED BINARY! to convert decimal");
+scanf("%d", &num);
+int temp = num;
+
+while (temp) {
+	int last = temp % 10;
+	temp = temp / 10;
+
+	decimal += last * e;
+	e = e * 2;
+
+}
+printf("%s %d\n", "Decimal: ", decimal);
+
+	return 0;
+}
diff --git a/test2.c b/test2.c
new file mode 100644
index 0000000..2bf8074
--- /dev/null
+++ b/test2.c
@@ -0,0 +1,13 @@
+#include <stdio.h>
+
+int main() {
+int n = 4, a = 1;
+int i, c;
+	for (i = 1; i <=n; i++) {
+		for (c = 1; c <= i; c++) {
+			printf("%d", a);
+			a++;
+		}
+		printf("\n");
+	}
+}
\ No newline at end of file