ruby - Why does Rspec of RubyMonk says it true where the outcome is false? -

ruby - Why does Rspec of RubyMonk says it true where the outcome is false? -

i have this:

def kaprekar?(k) string_k = (k * k).to_s length_k = k.to_s.length.to_i length_k2 = string_k.to_s.length.to_i number1 = string_k[0...length_k].to_i number2 = string_k[length_k..length_k2].to_i number1 + number2 == k end

and according error message 297 output true.

returns true 297

rspec::expectations::expectationnotmeterror

expected false true

but when same on repl.it see output:

kaprekar?(297) string_k : 88209 length_k : 3 length2 : 5 number1 : 882 number2: 9 => false

which right answer.

can explain why rubymonk outcome true?

edit 1:

the task is:

problem statement

9 kaprekar number since 9 ^ 2 = 81 , 8 + 1 = 9

297 kaprekar number since 297 ^ 2 = 88209 , 88 + 209 = 297.

in short, kaprekar number k n-digits, if square , add together right n digits >to left n or n-1 digits, resultant sum k.

find if given number kaprekar number.

can explain why rubymonk outcome true?

rubymonk actually saying expected outcome true, whereas implementation yields false. edit states 297 is kaprekar number. reply clarify this.

quoth kaprekar's number rubymonk (emphasis mine):

for kaprekar number k n-digits, if square , add together the right n digits left n or n-1 digits, resultant sum k.

given k = 297

→ n = 3

→ k2 = 88,209

→ right n digits = 209

→ left n-1 digits = 88

→ 209 + 88 = 297

→ right n digits + left n-1 digits = k

∴ kaprekar?(297) should homecoming true.

your solution adds the left n digits (882), right n-1 (09), why false (882 + 09 ≠ 297).

a sample solution, using array slicing negative indices, may like:

def kaprekar?(k) n = k.to_s.size square = (k * k).to_s right = square[-n..-1].to_i left = square[0...-n].to_i right + left == k end

ruby