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wolfgang
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Two friends met,the first one asked his friend:

sorry I forget your children`s ages...how old are they?

"if you multiply their ages,you`ll get 36" replied the other.

Hmmmm...still I can not guess.

and if you add their ages together, you`ll get your house number.

"give more hints,please"..

ok....the old one has black hair ,where as the last two are twins.

How old are those children?

Edited by wolfgang
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It's easier if you write out possibilities.

so three numbers multiplied to get 36:

1,1,36

1,2,18

1,3,12

1,4,9

1,6,6

2,2,9

2,3,6

3,3,4

I think thats everything. Let me know if there are more.

Then we get their sums.

1,1,36=38

1,2,18=21

1,3,12=16

1,4,9=14

1,6,6=13

2,2,9=13

2,3,6=11

3,3,4=10

Now,the second friend would have guessed the ages of his children by now; since the sums (house numbers) are all different. But since he still cannot figure it out, it must be the two sets of numbers (1,6,6 and 2,2,9) that have the same sum.

And finally, since he said "oldest one", the oldest cannot be twins. 1,6,6 is impossible, therefore the ages are 2,2 and 9.

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I don't think the question as stated is limited to 3 children. It says "the last two are twins".

This would allow..

1,1,2,2,9 sum 15

1,1,4,9 sum 15

I believe this satisfies the criteria of the question and follows the logic of Aaryan's solution.

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I guess this can be done with more ease. We need two numbers (older and younger)with product 36. Possibilities are;

9 x 4

12 x 3

12 x 2

The younger ones are twins so we break the 'small' number in the above options.

9 x 2 x 2 = 36 - possible

12 x 3 x 1 - not possible

12 x 2 x 1 - not possible

We have our answer. Older one is 9 and younger twins are two. The puzzle is restricted to three kids. More combinations will only mean another set of an year old twins and multiplying them with other numbers wont change the equation.

Hair color, door number, etc. are waste information.

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