yes 10 simultaneously as that would insure that the brain is mostly destroyed at once, thus negating any pain, unlike lethal injection etc which cause considerable pain, and as justice should be about punishment and not revenge it makes more sense..
Lethal injection doesn't cause pain.
Lethal injection in Florida and most states of America involves a three-step process: sodium pentothal to stop the pain, pancuronium bromide to paralyse, and potassium chloride to trigger a fatal heart seizure.