You are working on an undercover spy mission, equipped with an iPhone to communicate with your partner. Assigned as the lookout, your job is to make sure that no nosy guards pass by and to alert your partner (through text! :D) if anyone does.

As the night drags on, you feel drowsy and for a brief moment, your phone slips from your hand. Startled, but unable to look away from your binoculars, you fumble around for your phone and eventually grab it.

However, after the brief tumble, there is no way of telling if the screen of the phone is on or off. Should it be on, the light would blow your cover, risking not only the mission but also your partner's life.

Without looking at the screen, what is a sequence of button presses that can guarantee the iPhone is off?

  • 1
    $\begingroup$ Ahhh... After reading through the whole story, I just realized that I don't have (and never had) an iPhone. Your turn, Apple guys! $\endgroup$
    – WhatsUp
    Nov 9, 2019 at 17:05
  • $\begingroup$ does the puzzle only work with an iphone or can I solve for android as well? $\endgroup$
    – Krash
    Nov 9, 2019 at 17:54
  • $\begingroup$ if the light is on, it would blow your cover. Sounds like we should just assume it's off cause it would be too late if it weren't! :) $\endgroup$
    – SteveV
    Nov 9, 2019 at 18:12
  • $\begingroup$ @Krash I chose an iPhone because the solution I have in mind works for an iPhone, but I'm not sure whether it'll work for android. $\endgroup$
    – jazhang
    Nov 9, 2019 at 21:29

1 Answer 1


You can:

Press the home button, then press the power button (very briefly)
On my iPhone 5/7, this keeps the screen off regardless of the initial state. However, do be careful to not press the buttons for too long, otherwise a phone that was initially off may turn on.

  • $\begingroup$ rot13(Abg fher ubj vg'f tbaan jbex ba vCubarf gung ab ybatre pneel gung ohggba) $\endgroup$
    – Avi
    Nov 9, 2019 at 19:02
  • $\begingroup$ rot13(Nuu V sbetbg nobhg gur arjre cubarf jvgubhg gur ubzr ohggbaf. Naljnlf, lbhe nafjre jnf jung V jnf guvaxvat bs!) $\endgroup$
    – jazhang
    Nov 9, 2019 at 21:32

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