Fixed a typo in equation explanation part (#447)

Prakash-Jha-Dev · jakobkogler · commit b7d746057e7f · 2019-07-26T12:22:12.000+02:00
diff --git a/src/algebra/montgomery_multiplication.md b/src/algebra/montgomery_multiplication.md
@@ -118,7 +118,7 @@ struct u256 {
         u64 a = x >> 64, b = x;
         u64 c = y >> 64, d = y;
         // (a*2^64 + b) * (c*2^64 + d) =
-        // (a + c) * 2^128 + (a*d + b*c)*2^64 + (b*d)
+        // (a*c) * 2^128 + (a*d + b*c)*2^64 + (b*d)
         u128 ac = (u128)a * c;
         u128 ad = (u128)a * d;
         u128 bc = (u128)b * c;
