## Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

### Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

# why?

In the main code, outside of the function, use the new mimic_array_sum() function you just wrote. Store the return value in a variable called \$sum, and then display that sum to the screen.

Bummer! It looks like you have not created a variable named \$sum in your main code, outside of the function. Please create it and store the return value from the mimic_array_sum function call in it.

palindromic_primes.php
```<?php

function mimic_array_sum(\$array) {

foreach(\$array as \$number) {
\$sum += \$number;
}

return \$sum; //return the value of \$sum

}
\$sum = mimic_array_sum(\$sum);
echo \$sum;

\$palindromic_primes = array(11, 757, 16361);

?>
```

You were pretty close, you need to pass an array, not the variable sum into the mimic_array_sum function:

```<?php

\$sum = 0;

function mimic_array_sum(\$array) {

foreach(\$array as \$number) {
\$sum += \$number;
}

return \$sum; //return the value of \$sum

}

\$sum = mimic_array_sum(array(11, 757, 16361));
echo \$sum;

\$palindromic_primes = array(11, 757, 16361);

?>
```

You're passing to your new `mimic_array_function` and argument of `\$sum`, however that variable does not exist anywhere in a scope that your function can access it. So essentially you're passing your function the value of `nil`. Instead of passing it `\$sum` you need to pass it something it can add, like that `\$palindromic_primes` variable which we know has an array of numbers.

thank you!