How to split a Number to Natural Numerals in Ruby -

for example:

input: 15

output:

15 = 1+2+3+4+5

15 = 4+5+6

15 = 7+8

input: 4

output: cannot split

here's 1 way:

def natural_numerals(value)   results = []   (1..value-1).each {|i| (i..value-1).each {|j| results << (i..j).to_a.join("+") if (i+j)*(j-i+1)/2 == value}}   if results.empty? nil else results end end  output1 = natural_numerals(15) output2 = natural_numerals(4)  puts output1.inspect #=> ["1+2+3+4+5", "4+5+6", "7+8"] puts output2.inspect #=> nil