Unit 5 Contents

2. Make a table like the one below, and fill in the missing entries.

3. What does the mystery machine do? There are many ways to answer this question.
   You can write the answer in words: The mystery machine is an “add ten machine.”
   
   You can write the answer in symbols. If we use N to stand for the Input number, then:
   
   N + 10 = Output
   
4. If you are given an output number, how can you find the input number?

The doubling machine and the mystery machine that Irma and Luis found in the attic were similar: for every number that went into the machine, an output number came out. One machine followed the doubling rule and the other followed the “add 10” rule to get the output number.

In mathematics, a rule that gives an output for every input is called a function. The first machine used the doubling function. The second machine used the “add ten” function.