Jump to content
BrainDen.com - Brain Teasers
  • 0

The root of the matter


bonanova
 Share

Question

This is a participatory puzzle. You must participate.

Write down three consecutive integers. There is no restriction, but your workload will be lighter if you pick small ones. Seriously. Write them down. I will wait.

Cube them - that will give you three larger, nonconsecutive integers. Now add their digits. Example: one of your original integers was 347. Remember I said it would be easier to use smaller ones? But does anyone listen any more? 3473 is 41,781,923. 4+1+7+8+1+9+2+3 = 35. Keep going. 3+5 = 8. OK now you can stop.

Do this for each of your three integers. Order the results, largest to smallest, to form a new three-digit number. Great job! You're all done. Except, now you have to read the spoiler.

Your new number is .... drum roll ... 981.

Your task is to debunk the rumor that I am psychic. Should not be hard.

Link to comment
Share on other sites

3 answers to this question

Recommended Posts

  • 0

In any set of 3 consecutive numbers:

One of them will be a multiple of 3. When you cube the number, there will be a factor of 3*3*3. 3*3=9. All multiples of 9 have the property that the sum of their digits is divisible by 9.

One of them will be 1 less than a multiple of 3 (3x-1). All cubes of (3x-1) have the property that the sum of their digits is 8 (if you keep adding until you get a single digit). 1^3 =1. 9-1=8.
One of them will be 2 less than a multiple of 3 (3x-2). All cubes of (3x-2) have the property that the sum of their digits is 1 (if you keep adding until you get a single digit). 2^3=8. 9-8=1.

Link to comment
Share on other sites

  • 0

This is a participatory puzzle. You must participate.

Write down three consecutive integers. There is no restriction, but your workload will be lighter if you pick small ones. Seriously. Write them down. I will wait.

Cube them - that will give you three larger, nonconsecutive integers. Now add their digits. Example: one of your original integers was 347. Remember I said it would be easier to use smaller ones? But does anyone listen any more? 3473 is 41,781,923. 4+1+7+8+1+9+2+3 = 35. Keep going. 3+5 = 8. OK now you can stop.

Do this for each of your three integers. Order the results, largest to smallest, to form a new three-digit number. Great job! You're all done. Except, now you have to read the spoiler.

Your new number is .... drum roll ... 981.

Your task is to debunk the rumor that I am psychic. Should not be hard.

if I choose -2, -1, 0, won't this fail? -2 cubed = -8, -1 cubed is -1, and 0 cubed is 0. Arranged from least to greatest is 0,-8,-1.

.

Link to comment
Share on other sites

  • 0

This is a participatory puzzle. You must participate.

Write down three consecutive integers. There is no restriction, but your workload will be lighter if you pick small ones. Seriously. Write them down. I will wait.

Cube them - that will give you three larger, nonconsecutive integers. Now add their digits. Example: one of your original integers was 347. Remember I said it would be easier to use smaller ones? But does anyone listen any more? 3473 is 41,781,923. 4+1+7+8+1+9+2+3 = 35. Keep going. 3+5 = 8. OK now you can stop.

Do this for each of your three integers. Order the results, largest to smallest, to form a new three-digit number. Great job! You're all done. Except, now you have to read the spoiler.

Your new number is .... drum roll ... 981.

Your task is to debunk the rumor that I am psychic. Should not be hard.

if I choose -2, -1, 0, won't this fail? -2 cubed = -8, -1 cubed is -1, and 0 cubed is 0. Arranged from least to greatest is 0,-8,-1.
.

You're right.

The integers must be positive.

Good catch.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...