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```ruby
[4, 4, 5, 6].then { |ord|
%i[+ - * /].repeated_combination(ord.size - 1).flat_map { |orr|
(ord + orr).permutation((ord + orr).size).map { |formula|
begin
formula if formula.each.with_object([]) { |v, obj|
if v.is_a? Symbol
fail unless obj.size >= 2
fail if v == :/ && obj[-1].zero?
obj[-2, 2] = obj[-2].send(v, obj[-1])
else
obj << v.to_r
end
}.first == 10
rescue
end
}
}
}.compact
```