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Math Brain Teaser with a Hen

If a hen and a half lay an egg and a half in a day in and a half, how many eggs will six hens lay in seven days?

In order for your brain to get the most exercise and benefit from these puzzles, really try to come up with the answer on your own before scrolling down to the comments below.

22 Comments to “Math Brain Teaser with a Hen”

  1. Joe | Guest

    (1.5 hens)*(1.5 days)=(1.5 eggs)
    2.25(hens*days)=(1.5 egg)
    (1 hen*1 day)=(2/3) egg
    6*7*((1hen*1day)=(2/3) egg)
    42(hens*days)=28 eggs
    They’ll lay 28 eggs.

  2. Christine | Guest

    (1.5 Hens) => (1.5 Eggs) =>(1.5 Days)
    3H => 3E =>1.5D
    6H => 6E =>1.5D
    6H => 12E =>3D
    6H =>4E =>1D
    6H => XE =>7D
    => 6 Hens => 4 * 7 = 28 Eggs => 7 Days

  3. Michael | Guest

    1.5H x 1.5D = 1.5E
    1.5(H x D) = 1.5E
    H x D = E
    6 x 7 = 42 eggs

  4. Rhys | Guest

    7. Duh. =P

  5. coupland | Guest

    Trick question. Hens don’t lay eggs, they lay roosters.

  6. Kyle | Guest

    The hens and the eggs are variables and the days are your constants. So, six hens will lay six eggs in a day and a half. Now, on the third day, double the amount of eggs you have to get 12 eggs. On the sixth day double 12 to get 24. By the end of the seventh day (from the beginning) the hens will have layed 2/3 of an egg each. Take 2/3*6 to get 4 total, 4+24=28 eggs. Booyaka.

  7. Prairie Kittin | Guest

    If one and a half hens lays one and a half roosters, how many eggs will the hen and a half lay in one and a half day?

    And, what happens to the half rooster? Does he go off half cocked?


    (I will understand if this post gets moderated out! ROFL!!!)

  8. Richard | Guest

    Or do it like your head would do it.

    1.5 hens output 1.5 eggs in 1.5 days
    1.5 hens output 1.0 eggs in 1.0 days
    6.0 hens output 4.0 eggs in 1.0 days

    4.0 * 7.0 = 28.0 eggs in 7 days

  9. Carl | Guest

    I was gonna write out the response, but I would write the same formula as Michael. The other responses remind me of what Bush calls “fuzzy math”

    42 eggs would be my answer

  10. Luc Lodder | Guest

    You all miss the word IN in the first sentence.

    It say: “…in a day IN a half..”
    And not: “…in a day and a half..”

    So… I would say:

    1,5 hens lay in 0,5 day = 1,5 eggs
    so 1,5 eggs are done in 12 hours by 1,5 hen.

    so 1,5 eggs are done in 8 hours by 1 hen.
    one hen can lay 3 eggs in 1 day (8×3=24)

    so 6 hens lay 6×3=18 eggs a day
    And in 7 day’s that is 7×18=126 eggs

  11. Adam | Guest

    Well, if 1.5 hens produce 1.5 eggs within any time frame, I think it’s much easier to start out realizing that 1 hen would lay 1 egg in the same time frame.

    (This is assuming the 1 hen is not stressed out from missing his halfling of a friend… of course not having a mangled half of hen next to you might also increase your productivity… but I digress.)

    Anyway, given that the time frame is 1.5 days, 6 hens would obviously lay 6 eggs in 1.5 days.

    So to find out how many eggs these same 6 hens would produce in 7 days, you just solve for X in the following equation:
    6 / 1.5 = X / 7

    So every 7 days, these 6 hens would produce 28 eggs.

  12. RLP | Profile

    As Luc points out, ‘in’ should’ve been typed ‘and’. Sorry about that

  13. Jim | Guest

    Is it



    7D=6 1/6E

  14. Jim | Guest

    err… no I don’t think it is

    1c = 1e =1d

    6c = 6e * 7d = 42e


  15. steven | Guest

    1.5 days / 1 egg from each hen

    7 / 1.5 = 4.666666666…. eggs per hen per 7 days

    4.666666666666…. * 6 = 28 eggs

  16. Leonard | Guest

    Since it takes 1.5 days for 1.5 hens to lay 1.5 eggs, 6 hens will lay 6 eggs per 1.5 days. With only 4 full 1.5 days within 7 days, I think there should be 24 eggs (6 eggs x 4 days) in total.

  17. Luc Lodder | Guest

    Well, changing the IN in AND is not fair, now I have to recalculate :D

  18. fantabulous | Guest

    24 eggs in effectively 6 days only because on the 7th day they still cannot produce the next set of 1 and half egg.

  19. Ian Mckinnon | Guest

    i got 42 somehow.

  20. keith | Guest

    its 28

  21. Hen Puzzle Redux - Smartkit Brain Enhancement News | Guest

    […] [submitted by a reader who liked this brain teaser] […]

  22. Sarah Al Taher | Profile

    each egg needs day and a half so 7 days 4 (1.5) or : [7/1.5] = [4.67] = 4
    six hens>>>> 4*6=24 eggs.

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