diff --git a/assignments/a4/a4_test.py b/assignments/a4/a4_test.py
new file mode 100644
index 0000000..d5f4983
--- /dev/null
+++ b/assignments/a4/a4_test.py
@@ -0,0 +1,62 @@
+import math
+
+import numpy as np
+from matplotlib import pyplot as plt
+
+from assignments.a4.a4_part2 import starting_coprime_numbers
+
+
+def plot_eq(f, lower, upper, step=0.1):
+    x_p = list(np.arange(lower, upper, step=step))
+    y_p = [f(x) for x in x_p]
+    plt.plot(x_p, y_p, color='#ffcccc')
+
+
+# Initialize a list
+primes = []
+for possiblePrime in range(2, 1000):
+
+    # Assume number is prime until shown it is not.
+    isPrime = True
+    for num in range(2, possiblePrime):
+        if possiblePrime % num == 0:
+            isPrime = False
+
+    if isPrime:
+        primes.append(possiblePrime)
+
+
+def coprime_to_all(primes: set[int], n: int) -> int:
+    """Return the positive integers less than n that are coprime to every number in primes.
+
+    Preconditions:
+        - primes != set()
+        - every element of primes is prime
+        - n >= math.prod(primes)
+    """
+    m = math.prod(primes)
+    nums_so_far = starting_coprime_numbers(primes)
+    phi = len(nums_so_far)
+    count = 0
+    while nums_so_far[-phi] + m < n:
+        next_number = nums_so_far[-phi] + m
+        list.append(nums_so_far, next_number)
+        count += 1
+
+    # print('m =', m)
+    # print('phi(m) =', phi)
+    # print('n * phi(m) / m =', n * phi / m)
+    # print('n * phi(m) / m - phi(m) =', n * phi / m - phi)
+    # print('count =', count)
+
+    return count
+
+
+if __name__ == '__main__':
+    x = primes
+    plt.plot(x, [coprime_to_all({a}, 2000) for a in x], label='count')
+    plt.plot(x, [2000 - a for a in x], label='count')
+
+    plt.ylabel('loop count')
+    plt.xlabel('m')
+    plt.show()