Checking the Remainder of Division in PHP

Let we have two variables with numbers:

php<?php
  $a = 10;
  $b = 3;
?>

Let's find the remainder of dividing one variable by another:

php<?php
  $a = 10;
  $b = 3;
  
  echo $a % $b; // outputs 1
?>

Now let the variables store such values that one variable is divisible by the second without a remainder:

php<?php
  $a = 10;
  $b = 5;
  
  echo $a % $b; // outputs 0
?>

Let's write a script that will check whether one number is divisible by the second without a remainder:

php<?php
  $a = 10;
  $b = 3;
  
  if ($a % $b === 0) {
    echo 'divisible without remainder';
  } else {
    echo 'divisible with remainder';
  }
?>

Now let it be required, if the number is divisible with a remainder, to display this remainder on the screen:

php<?php
  $a = 10;
  $b = 3;
  
  if ($a % $b === 0) {
    echo 'divisible without remainder';
  } else {
    echo 'divisible with remainder ' . $a % $b;
  }
?>

In the code above, it turns out that the remainder is calculated in two places, which is not optimal.

Let's fix the problem:

php<?php
  $a = 10;
  $b = 3;
  $rest = $a % $b;
  
  if ($rest === 0) {
    echo 'divisible without remainder';
  } else {
    echo 'divisible with remainder ' . $rest;
  }
?>