Fixnum and BigNum are deprecated, and the test code used for this exercise is returning an error because of that.

https://apidock.com/ruby/Fixnum

https://apidock.com/ruby/Bignum

workarund:

Fixnum = Integer
BigNum = Integer
def sum_terms(n)
  (1..n).reduce(0) { |current, x| (x*x + 1) + current}
end

https://apidock.com/ruby/Fixnum

Deprecated long ago, should probably be updated to test whether it's an Integer.

I'm not sure but it seems like there is an error wit Fixnum and Bignum classes, so one of the monkey patch could be:

class Integer
    def is_a?(klass)
        return true if klass == Fixnum || klass == Bignum
        super
    end
end

class Fixnum < Integer end

class Bignum < Integer end

That’s a great breakdown of how reduce works, kind of like how an Acne Fighting Patch steadily works on a problem by building results over time through small, consistent actions.

can anyone having corrected code