pr -l 63 factorial.ex       >factorial.pr
pr -l 63 fibonacci.ex       >fibonacci.pr
pr -l 63 exponentiation.ex  >exponentiation.pr
pr -l 63 gcd.ex             >gcd.pr
pr -l 63 sqrt.ex            >sqrt.pr
pr -l 63 sqrt2.ex           >sqrt2.pr
pr -l 63 summation.ex       >summation.pr
pr -l 63 derivative.ex      >derivative.pr
chmod 644 *.ex *.pr