Find a three-digit number containing three different digits

  • Thread starter Greg Bernhardt
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In summary, the conversation discusses finding a three-digit number containing three different digits where the sum of the first digit and the number formed by the second and third digits, the first digit multiplied by the number formed by the second and third digits, and the sum of the three digits are all perfect squares. The conversation also addresses the question of whether zero should be considered a perfect square and provides two possible solutions to the problem (036 and 081). The conversation also delves into the math method used to find the solutions and offers to provide more difficult brain teasers if requested.
  • #1
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Find a three-digit number containing three different digits where the following are all perfect squares:

(A) The sum of the first digit and the number formed by the second and third digits;
(B) The first digit multiplied by the number formed by the second and third digits and
(C) The sum of the three digits.
 
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  • #2
In the midst of figuring this out I found out that I need to know if you consider zero a perfect square - some people do.

Assuming that you do my answer is

036

0 + 3 + 6 = 9
0 + 36 = 36
0 x 36 = 0


also "081"

If not, I am still finishing up all the possible ones without zeros...
 
  • #3
916
 
  • #4
A little bit about the math method I used, being a freakin' genius!

First off - assess which requirement narrows the answers down. It's the last one.

Any such X Y Z numbers must be at least one, and at greatest nine.

So at least 1 + 1 + 1
and at greatest 9 + 9 + 9

3 to 27

There are only 4 PS in that range:

4 - 9 - 16 - 25

So the only possible XYZ number is numbers that add up to those.

4 can easily be done with only a few variables. Nine takes a bit more...


4 and nine both have no such answers needed.

So on to 16, which has just the one I mentioned.

How many does 25 have? I didn't bother once I finally got one - but maybe greg knows!

My guess is less than 4!
 
  • #5
Hey Greg - I am new here and like this brain teaser thing.

I was wondering - I could provide some very difficult questions, ones that no one could find the answer to online, and would truly require some brain "teasing". Just PM me or something if you'd like to view any of them, thanks!
 

1. What is the maximum possible number that can be formed using three different digits?

The maximum possible number that can be formed using three different digits is 987. This is because the largest digit, 9, can only be used in the hundreds place and the smallest digit, 0, cannot be used at all.

2. Is it possible for the three-digit number to contain a zero?

No, a three-digit number containing three different digits cannot have a zero in it. This is because the smallest digit, 0, can only be used in the tens or ones place, and a three-digit number requires all three places to be filled with different digits.

3. How many different three-digit numbers can be formed using three different digits?

There are 720 different three-digit numbers that can be formed using three different digits. This can be calculated by using the combination formula, nCr = n! / (r!(n-r)!), with n=10 (possible digits) and r=3 (places in a three-digit number).

4. Can the three-digit number have the same digit in more than one place?

No, a three-digit number containing three different digits cannot have any repeated digits. Each place in a three-digit number must be filled with a unique digit, so having the same digit in more than one place is not possible.

5. What is the smallest possible three-digit number that can be formed using three different digits?

The smallest possible three-digit number that can be formed using three different digits is 102. This is because the smallest digit, 0, cannot be used in the hundreds place, leaving 1 as the smallest possible digit in that place. The remaining two digits, 0 and 2, can then be placed in the tens and ones place, respectively.

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