From ab86fc16fe277d60cc16f0bbdf3711a59b3ab023 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Lema=C5=84czyk?= <marek@lemanczyk.eu>
Date: Thu, 16 Oct 2025 22:01:34 +0200
Subject: [PATCH] Fix quotient and remainder calculation in factor extraction

---
 PerfectNumbers.Core/PrimeOrderCalculator.cs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/PerfectNumbers.Core/PrimeOrderCalculator.cs b/PerfectNumbers.Core/PrimeOrderCalculator.cs
index 1f205cd..deebe72 100644
--- a/PerfectNumbers.Core/PrimeOrderCalculator.cs
+++ b/PerfectNumbers.Core/PrimeOrderCalculator.cs
@@ -1205,11 +1205,12 @@ internal static partial class PrimeOrderCalculator
 				continue;
 			}
 
-			// Use DivRem to reuse a single division for the quotient and remainder.
+			// Derive the remainder from the quotient to avoid an extra division.
 			int exponent = 0;
 			while (true)
 			{
-				ulong quotient = Math.DivRem(remainingLocal, primeCandidate, out ulong divisionRemainder);
+				ulong quotient = remainingLocal / primeCandidate;
+				ulong divisionRemainder = remainingLocal - (quotient * primeCandidate);
 				if (divisionRemainder != 0UL)
 				{
 					break;