Maths brainteaser.

Silentecho
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Re: Maths brainteaser.

Post by Silentecho » Mon Nov 02, 2015 6:54 pm

I never learnt that, so it's something important to remember.

Does X take precedence over / and + over - too, Brian1945, meaning we multiply first, then divide, add and subtract in that order?

Things could get very confusing if there were several different X / + - in the same operation and in jumbled order. Personally, I prefer the brackets system which makes it clearer and easier to calculate.

panama
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Re: Maths brainteaser.

Post by panama » Mon Nov 02, 2015 6:55 pm

Silentecho wrote:I never learnt that, so it's something important to remember.

Does X take precedence over / and + over - too, Brian1945, meaning we multiply first, then divide, add and subtract in that order?

Things could get very confusing if there were several different X / + - in the same operation and in jumbled order. Personally, I prefer the brackets system which makes it clearer and easier to calculate.
From that same wikipedia article (http://en.wikipedia.org/wiki/Order_of_operations)
The standard order of operations

The order of operations, or precedence, used in mathematics and many programming languages is expressed here:[citation needed]
terms inside parentheses or brackets exponents and roots multiplication and division As they appear left to right addition and subtraction As they appear left to right
This means that if a mathematical expression is preceded by one operator and followed by another, the operator higher on the list should be applied first. The commutative and associative laws of addition and multiplication allow terms to be added in any order and factors to be multiplied in any order, but mixed operations must obey the standard order of operations.

It is helpful to treat division as multiplication by the reciprocal (multiplicative inverse) and subtraction as addition of the opposite (additive inverse).

Silentecho
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Re: Maths brainteaser.

Post by Silentecho » Mon Nov 02, 2015 6:56 pm

panama wrote:It is helpful to treat division as multiplication by the reciprocal (multiplicative inverse) and subtraction as addition of the opposite (additive inverse).
Thanks, panama, that's made things much clearer. :shock: :mrgreen:

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 6:57 pm

Here's another - quite easy.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...


What about this?

By moving one of the following digits, make the equation correct. 62 - 63 = 1

And another.

What is special about the following sequence of numbers?
8 5 4 9 1 7 6 10 3 2 0

panama
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Re: Maths brainteaser.

Post by panama » Mon Nov 02, 2015 6:58 pm

bindeweede wrote:

What about this?

By moving one of the following digits, make the equation correct. 62 - 63 = 1
Move one of the - between 63 and 1 to the left to make 62=63-1

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 6:59 pm

panama wrote:
bindeweede wrote:

What about this?

By moving one of the following digits, make the equation correct. 62 - 63 = 1
Move one of the - between 63 and 1 to the left to make 62=63-1
No. You can only move the digits.

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 7:00 pm

Nobody else giving it a try?

Here's another.

If:
2 3 = 10
7 2 = 63
6 5 = 66
8 4 = 96
9 7 = ??

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Brian1945
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Re: Maths brainteaser.

Post by Brian1945 » Mon Nov 02, 2015 7:00 pm

144

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 7:01 pm

Correct Brian. Any ideas on the others?

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chaggle
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Re: Maths brainteaser.

Post by chaggle » Mon Nov 02, 2015 7:02 pm

By moving one of the following digits, make the equation correct. 62 - 63 = 1
Sorry, thought I answered this ages ago.

26 - 63 = 1
Don't blame me - I voted remain :con

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 7:02 pm

chaggle wrote:
By moving one of the following digits, make the equation correct. 62 - 63 = 1
Sorry, thought I answered this ages ago.

26 - 63 = 1
Correct. What about this?

What do the following numerals represent?

11111121113122223222

ETA. That one isn't too hard, but this one got me.

Here is a series of numbers. What is the next number in the sequence?
1
11
21
1211
111221
312211
13112221

??

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 7:03 pm

No takers then. I think this is called a "bump". :thumb:

What about this?

What do the following numerals represent?

11111121113122223222

ETA. That one isn't too hard, but this one got me.

Here is a series of numbers. What is the next number in the sequence?
1
11
21
1211
111221
312211
13112221

??[/quote]

Silentecho
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Re: Maths brainteaser.

Post by Silentecho » Mon Nov 02, 2015 7:04 pm

[quote="bindeweede"]Here's another - quite easy.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...


55

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bindeweede
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Re: Maths brainteaser.

Post by bindeweede » Mon Nov 02, 2015 7:04 pm

Silentecho wrote:
bindeweede wrote:Here's another - quite easy.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...


55
Yes. Have you tried the other one, Silentecho?

Silentecho
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Re: Maths brainteaser.

Post by Silentecho » Mon Nov 02, 2015 7:06 pm

bindeweede wrote:Have you tried the other one, Silentecho?
You mean this one?
bindeweede wrote:What is special about the following sequence of numbers?
8 5 4 9 1 7 6 10 3 2 0
Don't see the answer, no, or to your series of ones, twos and threes.

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