Sum of First N Natural Number in PHP
Last Updated :
16 Nov, 2023
Given a number N, the task is to find the sum of the first N natural numbers in PHP.
Examples:
Input: N = 5
Output: 15
Explanation: We will Add the Numbers till N
i.e. 1 + 2 + 3 + 4 + 5 = 15
Input: N = 10
Output: 55
There are different methods to find the sum of first N natural numbers, these are:
Using for Loop
We will iterate a loop from 1 to N and add all elements to get the sum of first N natural numbers.
Example:
PHP
<?php
$N = 5;
$sum = 0;
for ( $i = 1; $i <= $N ; $i ++)
$sum = $sum + $i ;
echo "Sum of first " . $N .
" Natural Numbers : " . $sum ;
?>
|
Output
Sum of first 5 Natural Numbers : 15
The mathematical formula to find the sum of first N natural number is N * (N + 1) / 2.
Example:
PHP
<?php
$N = 5;
$sum = $N * ( $N + 1) / 2;
echo "Sum of first " . $N .
" Natural Numbers : " . $sum ;
?>
|
Output
Sum of first 5 Natural Numbers : 15
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