diff --git a/src/CalcManager/Ratpack/conv.cpp b/src/CalcManager/Ratpack/conv.cpp
index 4f7609de..893da931 100644
--- a/src/CalcManager/Ratpack/conv.cpp
+++ b/src/CalcManager/Ratpack/conv.cpp
@@ -1171,7 +1171,7 @@ wstring NumberToString(_Inout_ PNUMBER& pnum, NumberFormat format, uint32_t radi
         {
             if (format == NumberFormat::Engineering)
             {
-                exponent = (eout % 3);
+                exponent = (3 + (eout % 3)) % 3;
                 eout -= exponent;
                 exponent++;