# Applying transformations to strings in JavaScript

Suppose we have the variable `num` with some number:

`let num = 12345;`

Let's find the number of digits in this number. As you already know, to find the length of a string, you can use the property `length`.

However, it only works on strings, and when applied to a number, it won't work:

`let num = 12345; alert(num.length); // shows undefined`

To solve the problem, we convert our number to a string and find the length of this string:

`let num = 12345; let str = String(num); // convert our number to a string alert(str.length); // find the length of the string`

You can not involve the intermediate variable `str`, but apply the property `length` immediately to the result of the function `String`:

`let num = 12345; alert(String(num).length); // find the length of the string`

Given a variable with a number. Find the number of digits in this number.

Given two variables with numbers. Find the number of digits in one and the second number, add the results and display it on the screen.

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