Interviewer: Square each digit of number without using any string function

Photo by Rahul Mishra on Unsplash

Recently I gave an interview for the role Sr. Frontend Developer. The Interviewer asked me this question:

Q: Square each digit of a given number — 9191 => 811811

Right after seeing the question I started implementing it, using inbuilt JavaScript function this was pretty much easy.

Here is the solution which I proposed:

After seeing this code, he wasn’t satisfied 😞, He asked me to do it without using any string functions.

I thought of a little but, and right after few seconds It was clear that if we have to do this without using string method then we have to do two extra things:

1. Reverse the number — because if we run a loop over number we will get result in reverse order.
2. Find the number of zero needs to be added to a number: We don’t know how big the square would be, so we need to dynamically find the number.

All these programs I wrote while I was in my college, so I simply have to recall those days and this was the piece of code which I came up with:

Square each digit of a number without using string function.

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