Sum even numbers from $a to $b - PHP Online
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Full code of Sum even numbers from $a to $b.php
- <?php
- $a = 11; // Replace with your desired lower limit
- $b = 111; // Replace with your desired upper limit
- $sum = 0;
- # simple solution (inefficient)
- for ($i = $a; $i <= $b; $i++) {
- if ($i % 2 == 0) {
- $sum += $i;
- }
- }
- echo "The sum of even numbers from $a to $b is: $sum", "\n";
- # Good solutuion = Formula
- $a += $a & 1;
- $b -= $b & 1;
- echo ($b/2 * ($b/2 + 1)) - (($a-2)/2 * (($a-2)/2 + 1));