Note: The Comments might spoil the answer, be careful.

Number game: use + – * / and parenthesis to make four numbers of 1..9 to a sum of 21. For example : 1 1 3 7 can be used so : 1-1+(3*7)

1) Use numbers : 3 3 8 8

2) Use number : 1 5 6 7


Testing Game, simple :

There is a closed room with three lamps inside. Outside there is are three switches. Each switch operates one lamp. Now, you have to figure out which switch operates which lamp, but you can only use two switches and look at the lamps after you had made all your switching. What do you do ?


Circle and a dot:

Draw a circle and a dot inside it without lifting the pen off paper.




13 thoughts on “Puzzles

  1. #ยค%”#%&”#%

    Can you pls verify if your second one is correct? ๐Ÿ™‚ Although I cannot prove it is incorrect.


    – Turned the answer to gibberish. But it was correct.

    • Hi

      The 3,3,8,8 is correct. The answer i was looking for.
      The second one is solvable. There is at least one answer that i know is correct and gives 21. Have you tried all the combinations ?

  2. ********* is the solution if the order doesn’t matter

    I don’t think there is a solution for the order 1 5 6 7

    – Changed the solution to gibberish so it would not be revealed to others.
    But yes, the order does not matter.

  3. Walk into the room and gently rub each bulb with a thin layer of maple syrup.

    Turn on any switch. Wait 5 minutes. Turn on a second switch and immediately sprint into the room. The bulb that is is crackling and smelling like burnt toxic waste is connected to the first switch. The light that is starting to gently smoke is connected to the second switch. The light that is off (assuming, of course, that all three bulbs work!) is connected to the switch that was not flipped.

    If you prohibit me from rubbing maple syrup on the bulbs in question, fine, be that way. I’ll Perform the same operation sans syrup and touch both bulbs with equal force with each of my palms after my sprint. The bulb that burns me more thoroughly is the one that was turned on first.

  4. Answer for third question

    1. switch on first lamp – wait for few minutes
    2. switch on second lamp
    3. Immediately feel the heat of the lamps – more heated lamp is the first one, other lighted one is second lamp and remaining one is third.

    Please let me know, if you have any other answer.

    • Your answer is in essence the way to go. I would switch off the first lamp when I switch on the second. Therefore it is easier to distinguish between two “off” lamps which was operated by which switch.

  5. Circle and a dot:

    Draw a circle and a dot inside it without lifting the pen off paper.

    One way to do it is:
    – Take the paper and place a dot (try to make it a little bigger dot) in the center with pen.
    – Without lifting the pen, gently fold paper to pen’s nib.
    – Draw and line or semi circle on the folded paper and bring it back to the paper underneath the fold and far from the dot.
    – Then unfold the paper without lifting pencil, draw the circle

    Is this the way to do it? Any other possibilities?

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