diff --git a/pset1/1-add.c b/pset1/1-add.c
new file mode 100644
index 0000000..e09b06a
--- /dev/null
+++ b/pset1/1-add.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+int main(void) {
+  // initialization
+  int i1, i2;
+  // get input from user
+  scanf("%i %i", &i1, &i2);
+  // print answer!!
+  printf("The sum is %i and the difference is %i.", i1 + i2, i1 - i2);
+}
diff --git a/pset1/2-stdio.c b/pset1/2-stdio.c
new file mode 100644
index 0000000..bdc2449
--- /dev/null
+++ b/pset1/2-stdio.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+int main(void)
+{
+	//initialization
+	char sex;
+	int age;
+	float height;
+
+	//get input from stdin
+	scanf("%c %i %f", &sex, &age, &height);
+	
+	//print answer to stdout
+	printf("The sex is %c, the age is %i, and the height is %f.", sex, age, height);
+	return 0;
+}
diff --git a/pset1/3-math.c b/pset1/3-math.c
new file mode 100644
index 0000000..d854f4f
--- /dev/null
+++ b/pset1/3-math.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+int main(void) {
+  // initialization
+  double a, b, c, d;
+  scanf("%lf %lf %lf %lf", &a, &b, &c, &d);
+
+  // print answer
+  printf("%lf", (a + b) * (a - b) + c / d);
+
+  return 0;
+}
diff --git a/pset1/4-pi.c b/pset1/4-pi.c
new file mode 100644
index 0000000..51abe65
--- /dev/null
+++ b/pset1/4-pi.c
@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+const double PI = 3.14159265;
+
+int main(void) {
+  // initialize values
+  double radius;
+  scanf("%lf", &radius);
+
+  // print answer
+  printf("The perimeter is %.4lf, the area is %.4lf.\n", PI * radius * 2,
+         PI * radius * radius);
+
+  return 0;
+}
diff --git a/pset1/5-data-types.c b/pset1/5-data-types.c
new file mode 100644
index 0000000..d71cfe0
--- /dev/null
+++ b/pset1/5-data-types.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+int main(void)
+{
+	//initialize variables
+	char a;
+	short b;
+	int c;
+	long d;
+	long long e;
+	float f;
+	double g;
+
+	//assign values from stdin
+	scanf ("%c %hd %i %ld %lld %f %lf", &a, &b, &c, &d, &e, &f, &g);
+
+	//print answers
+	printf("The 'char' variable is %c, it takes %ld byte.\n", a, sizeof(a));
+	printf("The 'short' variable is %hd, it takes %ld bytes.\n", b, sizeof(b));
+	printf("The 'int' variable is %i, it takes %ld bytes.\n", c, sizeof(c));
+	printf("The 'long' variable is %ld, it takes %ld bytes.\n", d, sizeof(d));
+	printf("The 'long long' variable is %lld, it takes %ld bytes.\n", e, sizeof(e));
+	printf("The 'float' variable is %f, it takes %ld bytes.\n", f, sizeof(f));
+	printf("The 'double' variable is %lf, it takes %ld bytes.\n", g, sizeof(g));
+
+	return 0;
+}