n = 5
 (1..40).step(n) {|y| puts y}

arr = [1, 2, 3, 4, 5, 6]
n = 3

for i in (n-1..arr.length - 1).step(n)
    puts arr[i]
end

(n-1..arr.length - 1).step(n) do |i|
    puts arr[i]
end

(n-1..arr.length - 1).step(n) { |i| puts arr[i] }

3
6

a = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
n = 2 # каждый 2-й

(n-1...a.length).step(n)
                .map(&a.method(:[]))
                .each(&method(:puts))
# 9
# 7
# 5
# 3
# 1

(1..2).map { |i| i.to_s }
(1..2).map(&:to_s) # <= то же самое

[1,2,3,4,5,6].each_with_index {|val, index| puts val if index % 2 == 0}