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# Mathematics Brain Teasers.

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Replace the dots in the following expression with positive numbers only to get a valid sum:

2.52 +... = 2.51.

Good luck.

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7 hours ago, seanjo said:

I can only do it using -ve 0.01. Will be interesting to see the solution.

I'll leave it unwnswered for a three days. After three days I'll post thr solution.

I'll give a hint tomorrow, and the next day.

Today's hint is positive numbers!

@sci-nerd @Guyver @Harte @RabidMongoose @Timothy @Dejarma I've seen you lot in the scientific section and Guyver is a quant, anyone interested trying to solve it. The solver can then post their own mathematical riddle so we can solve theirs.

Edited by danydandan
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10 hours ago, danydandan said:

Replace the dots in the following expression with positive numbers only to get a valid sum:

2.52 +... = 2.51.

Good luck.

2.52 + (i² / 10) = 2.51

The i is used in its imaginary number context. I haven't counted brackets or the divided and squared symbols as taking up a dot as they arent numbers. Do I get a cookie?

Edited by RabidMongoose
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1 minute ago, RabidMongoose said:

2.52 + (i² / 10) = 2.51

The i is used in its imaginary number context. Do I get a cookie?

Nope.

As I said just positive numbers.

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Just now, danydandan said:

Nope.

As I said just positive numbers.

They are lol

The squared operation is not a number, it only results in one which is -1

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1 minute ago, RabidMongoose said:

They are lol

The squared operation is not a number, it only results in one which is -1

I literally mean only positive numbers, as in no operators or anything.

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10 hours ago, danydandan said:

Replace the dots in the following expression with positive numbers only to get a valid sum:

2.52 +... = 2.51.

Good luck.

Well I play properly by replacing dots I can get:

2052 + 199 = 2251.

But I am left with the end dot. Is it a full stop?

Edited by RabidMongoose
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1 minute ago, RabidMongoose said:

Well I play properly by replacing dots I can get:

2052 + 199 = 2251.

But I am left with the end dot.

Positive numbers.

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Just now, danydandan said:

Positive numbers.

What so:

2152 + 299 = 2451

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1 minute ago, RabidMongoose said:

What so:

2152 + 299 = 2451

Yeah. Wooohoo.

Took a group of PhD students a whole day to figure out. Slippery slope when you only see the three dots after the plus.

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2 minutes ago, danydandan said:

Yeah. Wooohoo.

Took a group of PhD students a whole day to figure out. Slippery slope when you only see the three dots after the plus.

It took me about 20 minutes.

Mind you I have degrees too and a job I do maths and algebra in all day long.

Edited by RabidMongoose
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4 minutes ago, RabidMongoose said:

It took me about 20 minutes.

Mind you I have degrees too and a job I do maths and algebra all day long.

I was given it by a mathematician while I was a doing my master. I must admit it took awhile as I like others overcomplicated it.

Her reason for presenting it was to teach people that more often than not people overcomplicate maths problems. After she said it took my eight year old a few minutes to get.

So now it's your turm to present a mathematics riddle.

Edited by danydandan
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The answer for the sum 2+2 is the same as the answer for 2x2. Find a set of three different whole numbers whose sum is equal to their total when multiplied. So:

A + B + C = A x B x C

A=

B=

C=

Edited by RabidMongoose
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1 hour ago, RabidMongoose said:

The answer for the sum 2+2 is the same as the answer for 2x2. Find a set of three different whole numbers whose sum is equal to their total when multiplied. So:

A + B + C = A x B x C

A=

B=

C=

123.

1+2+3 is 6.

1.2.3 is 6.

Thus 1+2+3=1.2.3

Edited by danydandan
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14 hours ago, danydandan said:

Replace the dots in the following expression with positive numbers only to get a valid sum:

2.52 +... = 2.51.

Good luck.

Don’t want to read any responses. Just want to clarify the sum first please sir:

Does the . After the 2.51 count too? Or no?

I see it’s separated by a space, but just checking before I confuse myself more.

Edit: Possible solution, unless I don’t understand the riddle...

Spoiler

2152 + 199 = 2351 ?

If that’s right, then there should be multiple solutions

Edited by Timothy
Edit.
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2 minutes ago, Timothy said:

Don’t want to read any responses. Just want to clarify the sum first please sir:

Does the . After the 2.51 count too? Or no?

I see it’s separated by a space, but just checking before I confuse myself more.

No that dot doesn't count. My phone automatically puts a full stop when I press enter. But you don't have to use all the dots.

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4 minutes ago, danydandan said:

No that dot doesn't count. My phone automatically puts a full stop when I press enter. But you don't have to use all the dots.

Cool beans. Did I get it correct?

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9 hours ago, Timothy said:

Cool beans. Did I get it correct?

Yeap.

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Turn it up, they are decimal points inside those numbers, not "dots" ! You have gone dotty !

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4 minutes ago, Habitat said:

Turn it up, they are decimal points inside those numbers, not "dots" ! You have gone dotty !

Nope they are dots. How you choose to see them is entirely up to you. But they are ...........s. Some of them are decimal points some are operators and some are just dots. Can you please tell me which ones are just dots, just decimal points and just operators. Lol.

Edited by danydandan
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12 hours ago, danydandan said:

123.

1+2+3 is 6.

1.2.3 is 6.

Thus 1+2+3=1.2.3

If my response is correct, I know it is, can you confirm please. I'll post a new teaser when you can confirm.

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11 minutes ago, danydandan said:

Nope they are dots. How you choose to see them is entirely up to you. But they are ...........s. Some of them are decimal points some are operators and some are just dots. Can you please tell me which ones are just dots, just decimal points and just operators. Lol.

Even the dodgy question presupposes that people will assume the "dots" internal to those numbers are decimal points. Case dismissed !

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19 minutes ago, Habitat said:

Even the dodgy question presupposes that people will assume the "dots" internal to those numbers are decimal points. Case dismissed !

I know that's the point. But my question my rules and people have already gotten it. So I don't see the issue. Also the question was designed to show that people with too much knowledge usually over think things, I know I certainly do.

Did you see the new Coca-Cola ads for Australia? They are very upside down.

Edited by danydandan
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5 minutes ago, seanjo said:

Yeah I overthought it, I'm not exactly knowledgeable, but I thought there must be some mathematical expression that would allow a positive to become a negative...dull ****er I am!

The funny thing about it is, ask a bunch of 8-12 year olds and they'll answer it correctly, because they haven't advanced knowledge of mathematics.

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On 10/4/2018 at 12:30 AM, danydandan said:

Replace the dots in the following expression with positive numbers only to get a valid sum:

2.52 +... = 2.51.

Good luck.

The opposite of .01.

So, 2.52 + -(.01) = 2.51