Added Modular Exponential

Maths/ModularExponential.py

@@ -0,0 +1,20 @@
+def modularExponential(base, power, mod):
+	if power < 0:
+		return -1
+	base %= mod
+	result = 1
+
+	while power > 0:
+		if power & 1:
+			result = (result * base) % mod
+		power = power >> 1
+		base = (base * base) % mod
+	return result
+
+
+def main():
+	print(modularExponential(3, 200, 13))
+
+
+if __name__ == '__main__':
+	main()