1 files changed, 30 insertions, 2 deletions
diff --git a/number.cpp b/number.cpp
index fa62b00..12448de 100644
--- a/number.cpp
+++ b/number.cpp
@@ -108,8 +108,36 @@ number::operator*(const number &n) const
 {
     number result;
 
-    for (number i; i < n; ++i) {
-        result += *this;
+    if (n < UINT32_MAX && *this < UINT32_MAX) {
+        return number(1ull * to_uint32() * n.to_uint32());
+    }
+
+    int level = 0;
+
+    for (auto it_low: _operands) {
+        number intermediate;
+
+        std::uint32_t carry = 0;
+
+        for (auto it_high: n._operands) {
+            std::uint64_t tmp = 1ull * it_low * it_high + carry;
+
+            intermediate._operands.push_back(tmp & UINT32_MAX);
+
+            carry = tmp >> 32;
+        }
+
+        if (carry) {
+            intermediate._operands.push_back(carry);
+        }
+
+        for (auto j = 0; j < level; ++j) {
+            intermediate <<= 32;
+        }
+
+        result += intermediate;
+
+        ++level;
     }
 
     return result;