p dec1.to_i(10)         # => 123459
p hex2.to_i(16)         # => 180154659
p oct3.to_i(8)          # => 4009
p bin4.to_i(2)          # => 345
p "xyz9".to_i(10)       # => 0  If there is not a valid letter, 0 is returned.