<?php
// assign data to variables
$array = [5,56,23,1,89,3];
$number = 90;
// calculate distances between given number and each element of array
$distances = array_map(
function($el) use ($number) {
return abs($el - $number);
},
$array
);
var_dump($distances);
//get monimal distance position
$index = array_keys(
$distances,
min($distances)
)[0];
// print out closest number
echo "Closest number is: " . $array[$index];