"Scalars"

Ruby doesn't have scalars like Perl and Python do. Strings, integers, and floating point numbers are each individual classes. In practice, though, you can often use then interchangeably:

foo = "pie" bar = 3.14159 baz = 42 sum = bar + baz

But some things don't work as expected:

zero = '0' one = zero + 1 # doesn't work!

If you try to do that, you'll get the error message

TypeError: failed to convert Fixnum into String

In Ruby, numeric strings are not automatically converted to numbers. Instead, you need to use the to_i method to do the conversion explicitly:

zero = '0' one = zero.to_i + 1