Codewars-Calculating-with-functions
There must be a function for each number from 0 ("zero") to 9 ("nine") There must be a function for each of the following mathematical operations: plus, minus, times, divided_by Each calculation consist of exactly one operation and two numbers The most outer function represents the left operand, the most inner function represents the right operand Division should be integer division. For example, this should return 2, not 2.666666...: