diff --git a/calculate.py b/calculate.py
new file mode 100644
index 0000000000..6dc22cf124
--- /dev/null
+++ b/calculate.py
@@ -0,0 +1,33 @@
+import circle
+import square
+
+
+figs = ['circle', 'square']
+funcs = ['perimeter', 'area']
+sizes = {}
+
+def calc(fig, func, size):
+	assert fig in figs
+	assert func in funcs
+
+	result = eval(f'{fig}.{func}(*{size})')
+	print(f'{func} of {fig} is {result}')
+
+if __name__ == "__main__":
+	func = ''
+	fig = ''
+	size = list()
+    
+	while fig not in figs:
+		fig = input(f"Enter figure name, avaliable are {figs}:\n")
+	
+	while func not in funcs:
+		func = input(f"Enter function name, avaliable are {funcs}:\n")
+	
+	while len(size) != sizes.get(f"{func}-{fig}", 1):
+		size = list(map(int, input("Input figure sizes separated by space, 1 for circle and square\n").split(' ')))
+	
+	calc(fig, func, size)
+
+
+
diff --git a/docs/README.md b/docs/README.md
index 63f8727939..dcc59f1334 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1,10 +1,22 @@
+0
+# How to use calculator:
+1. Run `python calculate.py`
+2. Enter the figure name. Available are Circle, Square.
+3. Enter the function: Area or Perimeter.
+4. Enter figure sizes. Radius for circle, one side for square.
+5. Get the answer!
+
 # Math formulas
 ## Area
-- Circle: S = πR²
-- Rectangle: S = ab
-- Square: S = a²
+- Circle: `S = πR²`
+- Rectangle: `S = ab`
+- Square: `S = a²`
+- Triangle: `S = sqrt(p * (p-a) * (p-b) * (p-c))` where p is semiperimeter
 
 ## Perimeter
-- Circle: P = 2πR
-- Rectangle: P = 2a + 2b
-- Square: P = 4a
\ No newline at end of file
+- Circle: `P = 2πR`
+- Rectangle: `P = 2a + 2b`
+- Square: `P = 4a`
+- Triangle: `P = a + b + c`
+
+)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
diff --git a/triangle.py b/triangle.py
new file mode 100644
index 0000000000..fb41f60a52
--- /dev/null
+++ b/triangle.py
@@ -0,0 +1,6 @@
+def area(a, b, c):
+    return (a + b + c) / 2
+
+
+def perimeter(a, b, c):
+    return a + b + c