# Optimizing a repetition of heavy operations in JavaScript

In the previous lesson, repeated function calls actually take very little time, and our optimization will not save much. However, everything will be much worse if we call a "heavy" function several times, which is executed for quite a long time.

Let, for example, we have a function that finds divisors of a number:

`function getDivisorsSum(num) { let res = 0; for (let i = 1; i <= num; i++) { if (num % i === 0) { res += i; } } return res; }`

Obviously, this function is quite "heavy". So it would be a bad idea to write code like this:

`let num = 123456; if (getDivisorsSum(num) >= 10 && getDivisorsSum(num) <= 100) { console.log('+++'); } else { console.log('---'); }`

It is better, of course, to perform the "heavy" operation once and write the result into a variable, and then use this variable in the right places:

`let num = 123456; let sum = getDivisorsSum(num); if (sum >= 10 && sum <= 100) { console.log('+++'); } else { console.log('---'); }`

Optimize the code below:

`let num = 1233456789; if (getSumSquare(num) >= 10 && getSumSquare(num) <= 100) { console.log('+++'); } else { console.log('---'); } function getSumSquare(num) { let digits = String(num).split(''); let sum = 0; for (let digit of digits) { sum += digit ** 2; } return sum; }`
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