diff --git a/12/priklad.md b/12/priklad.md
new file mode 100644
index 0000000..ce4fd50
--- /dev/null
+++ b/12/priklad.md
@@ -0,0 +1,9 @@
+# priklad.py
+```python
+
+
+class Clovek:
+	def __init__(self, age, weight):
+		self.age = age
+		self.weight = weight
+```
\ No newline at end of file
diff --git a/13/fraction.md b/13/fraction.md
new file mode 100644
index 0000000..db4c1ed
--- /dev/null
+++ b/13/fraction.md
@@ -0,0 +1,71 @@
+# fraction.py
+```python
+#!/usr/bin/python
+
+from math import gcd # importuju greatest common divisor
+					 # aby se mi snaz kratily zlomky
+
+# definujeme novou tridu
+class Fraction:
+	
+	# definujeme co se ma dit pri vytvoreni objektu
+	def __init__(self, up, down):
+		self.up = up # self.up != up
+		self.down = down
+		self.base() # bude se hodit pri zbytku implementaci
+					# zarucuje ze nebudeme muset explicitne volat
+					# metodu `base` nikde jinde
+
+	# kraceni zlomku
+	# vsimneme si ze narozdil od funkci, u metod
+	# je v pohode i jiny typ vraceni z funkce nez
+	# jenom pomoci `return`
+	# - metoda muze menit objekt kterymu nalezi
+	def base(self):
+		divisor = gcd(self.up, self.down) # ziskavame nejvedsi spolecny delitel
+		if divisor > 1: # zjistujeme jestli muzeme kratit
+			self.up = self.up // divisor # znena sebe sama
+			self.down = self.down // divisor # a zase
+
+			self.base() # rekurze, slo by to udelat i snadneji
+
+	# scitani zlomku
+	def add(self, other):
+		return Fraction(self.up * other.down + other.up * self.down, self.down * other.down)
+				# ^- tohle mi zaruci ze se ten zlomek automaticky zkrati
+				# jelikoz tvorim novy objekt a v initu mam `self.base()`
+				# taky vracim jiny objekt a nemenim ty, ktere jsem dostal
+
+	# nasobeni zlomku
+	def multiply(self, other):
+		return Fraction(self.up * other.up, self.down * other.down)
+	
+	# odcitani zlomku
+	def subtract(self, other):
+		return Fraction(self.up * other.down - other.up * self.down, self.down * other.down)
+	
+	# deleni
+	# prosim tady nepouzivat pythonovsky deleni, je velice nepresny
+	def divide(self, other):
+		return Fraction(self.up * other.down, self.down * other.up)
+
+	# aby se mi to hezky printlo
+	def show(self):
+		return f"{self.up}/{self.down}"
+
+# testy
+
+for x in range(1, 4):
+	for y in range(1, 4):
+		a = Fraction(x, y)
+		b = Fraction(y, x)
+
+		print(f"\na: {a.show()}\nb: {b.show()}\n")
+
+		print("+", a.add(b).show())
+		print("*", a.multiply(b).show())
+		print("-", a.subtract(b).show())
+		print("/", a.divide(b).show())
+
+# ez
+```
\ No newline at end of file
diff --git a/README.md b/README.md
index 5403926..e8397ac 100644
--- a/README.md
+++ b/README.md
@@ -56,8 +56,12 @@ Učí profesor Kubis a docent Veškrna.
 + [rekurze](11/rekurze)
 
 ## 12
++ [priklad](12/priklad)
 + [tridy_a_objekty](12/tridy_a_objekty)
 
+## 13
++ [fraction](13/fraction)
+
 ## 
 + [code_gen](code_gen)
 + [site_gen](site_gen)