perl -Mbignum -e ' printf "%20.17f\n", 20.1;' 20.10000000000000142 perl -Mbigrat -e ' printf "%20.17f\n", 20.1;' 20.10000000000000142 perl -Mbigrat -e ' printf "%20.17f\n", 20+1/10; 20.00000000000000000