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docs/reference/js/call.md

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+# Call a Function
+
+How to call a function in your code. #docs #function #call #language
+
+### @parent js/language
+ 
+
+Type a function name in your code to call an existing [function](/microbit/js/function) in your script.
+
+### Call a function
+
+1. In the Touch Develop editor, click a line of code to open the on-screen [Code Keyboard](/microbit/js/editor).
+
+2. Click `code` to see the functions in your script.
+
+2. Click the function that you want to call.
+
+3. Click `store in var` to store the return value in a variable.
+
+### Example: the square function
+
+Here's a function called `square`, with a [Number](/microbit/reference/types/number) input parameter:
+
+```
+/**
+ * // returns the square of the input parameter x
+ * @param x TODO
+ */
+export function square(x: number) : number {
+    let result: number
+    return x * x
+    return result
+}
+```
+
+The following code calls the `square` function, passing it an input parameter (`x`), and storing the return value in the `result` variable:
+
+### ~hide
+
+```
+let x1 = 2
+```
+
+### ~
+
+```
+let result1 = square(x1)
+```
+
+Or this code, which displays the result of the `square` function (without first storing the value in a variable):
+
+```
+basic.showNumber(square(x1), 150)
+```
+
+### See all your functions
+
+To see a list of the functions in a script, open the script and then click `script` (in the upper-right corner). All of the functions appear under the **code** heading. Click on a function to open it in the editor.
+
+### See also
+
+[function parameters](/microbit/js/functionparameters), [create a function](/microbit/js/function), [return statement](/microbit/js/return)
+