Thank you for pointing out it ! It takes nearly twice in processing time and gives the result very close to libgmp. ===== /usr/bin/time sqlite3 < sum-test.sql count 6000008, sum: 37035049380.000160000000000 3.22user 0.02system 0:03.25elapsed 99%CPU (0avgtext+0avgdata 115324maxresident)k ===== /usr/bin/time sqlite3 < sum-decimal-test.sql count 6000008, sum: 37035049380.037200000000000 5.91user 0.02system 0:05.94elapsed 99%CPU (0avgtext+0avgdata 115428maxresident)k 0inputs+0outputs (0major+28063minor)pagefaults 0swaps ===== /usr/bin/time ./sum-test-gmp count: 6000008, sum: 0.370350493800372000496e11 0.13user 0.00system 0:00.13elapsed 100%CPU (0avgtext+0avgdata 1920maxresident)k 0inputs+0outputs (0major+72minor)pagefaults 0swaps =====