# I don't understand this function proposal

Tell us what’s happening:
" multiply the elements from `0` to `n` inclusive in an array to create the product of those elements"
e.g. 0 to 9 would be 0x1 , 0x2 , 0x3, 0x4 … or would be 0x1, 1x2, 2x3, 3x4 , 3x5, 3x6, 3x7, 3x8, 3x9 ?
could someone give me a e.g. of “sum( )” and “multiply( )”?

``````function multiply(arr, n) {
var product = arr[0];
for (var i = 1; i <= n; i++) {
product *= arr[i];
}
return product;
}
``````

Your code so far

``````
function sum(arr, n) {
// Only change code below this line

// Only change code above this line
}

``````

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Challenge: Replace Loops using Recursion

it is from index 0 to index n, not from number 0 to number n

and the result would be the multiplication of all numbers at indexes from 0 to n

for example, if n is 3 the function would do `arr[0] * arr[1] * arr[2] * arr[3]`

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The goal of this challenge:
" Write a recursive function, `sum(arr, n)` , that returns the sum of the elements from `0` to `n` inclusive in an array `arr` ."

with expected result (from challenge): "`sum([2, 3, 4], 1)` should equal 5."

^^ what @ilenia said `arr[0] + arr[1]` = 5

1 Like