Merge pull request freeCodeCamp#17 from bgroveben/beginner_math

Beginner Math Challenges added to challenge directory. Not added to challenges.json yet.

Author: Ethan-Arrowood

challenges/4.1.Addition/lesson.md

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+## Python Addition
+
+In Python, an integer (int) is one of 3 distinct numeric types.  
+- https://docs.python.org/3.6/library/stdtypes.html#numeric-types-int-float-complex  
+
+In this exercise, you will add two integers using the plus (+) operator.
+- https://docs.python.org/3.6/library/operator.html#operator.add
+- https://docs.python.org/3/library/operator.html#mapping-operators-to-functions  
+```
+>>> 2 + 2
+4
+```
+
+**_Instructions:_**  
+**Change the 0 so that total will equal 20.**

challenges/4.1.Addition/lesson_code.py

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+### Modify the code below ###
+
+total = 10 + 0
+
+### Modify the code above ###
+
+print(total)