diff --git a/euler3.php b/euler3.php
new file mode 100644
index 0000000..74e8975
--- /dev/null
+++ b/euler3.php
@@ -0,0 +1,39 @@
+<?php
+/*
+* Gnieark's anwser to euler problem 3
+* https://projecteuler.net/problem=3
+*/
+
+echo largestPrimeFactorOf(600851475143);
+function largestPrimeFactorOf($number){
+    $primesNumbers=array(2);//non considering value 1
+    $i=3; //begin to 3
+
+    while($i<sqrt($number)){
+        //echo $i;
+        //is $i a factorOf $number
+        if(fmod($number,$i)==0){
+            //is $i a prime number
+             $index=0;
+             $isPr=true;
+             while(($primesNumbers[$index]<sqrt($i)) && $index < (count($primesNumbers))-1){
+                    if((fmod($i,$primesNumbers[$index])==0)){
+                        $isPr=false;
+                        break;
+                    }
+                    $index++;
+            }
+            if($isPr){
+                $primesNumbers[]=$i;
+                $lastPr=$i;
+            }
+
+        }
+        $i=$i+2;
+    }
+    if (isset($lastPr)){
+        return $lastPr;
+    }else{
+        return 1;
+    }
+}
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