# Calculating Population Change Over Time with R Q10

Please can someone explain to me how to do Q10 (of 10) from the Introduction to R Course, Calculating Population Change Over Time with R.

I just don’t understand what it is asking me to do. What’s a results call, how do I do that? Basically, what is the answer, the code. It’s driving me mad.

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call the function to print a summary.

What’s a results call, how do I do that?

A call or invocation of a function is simply when you use the function.

If i have a function `foo()` that can just be done with

``````foo()
``````

for example the `print()` function is often called and it doesn’t return anything, instead it writes to the output.

If foo() returns something in it’s definition, that return can be assigned to a variable

``````result <- foo()
``````

So they’re asking you to call `calculate_annual_growth()` and pass in 5 arguments (that go in-between the parenthesis) and print that.

So the code might look like

``````print(calculate_annual_growth(x,y,z,v,w)
``````

where x, y, z, v, w are the corresponding arguments you put in (it’s in the description)

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