Maths brainteaser.

Silentecho
Posts: 44
Joined: Sun Oct 25, 2015 9:55 pm

Re: Maths brainteaser.

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
Posts: 549
Joined: Sun Oct 25, 2015 8:19 pm

Re: Maths brainteaser.

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
Posts: 44
Joined: Sun Oct 25, 2015 9:55 pm

Re: Maths brainteaser.

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.  bindeweede
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Location: Hertfordshire, UK

Re: Maths brainteaser.

Here's another - quite easy.

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

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
Posts: 549
Joined: Sun Oct 25, 2015 8:19 pm

Re: Maths brainteaser.

bindeweede wrote:

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

bindeweede
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Location: Hertfordshire, UK

Re: Maths brainteaser.

panama wrote:
bindeweede wrote:

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.

bindeweede
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Location: Hertfordshire, UK

Re: Maths brainteaser.

Nobody else giving it a try?

Here's another.

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

Brian1945
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Joined: Sun Oct 25, 2015 9:59 pm
Contact:

Re: Maths brainteaser.

144

bindeweede
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Location: Hertfordshire, UK

Re: Maths brainteaser.

Correct Brian. Any ideas on the others?

chaggle
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Joined: Mon Oct 26, 2015 10:01 am

Re: Maths brainteaser.

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 bindeweede
Posts: 3604
Joined: Sun Oct 25, 2015 3:45 pm
Location: Hertfordshire, UK

Re: Maths brainteaser.

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

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

??

bindeweede
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Joined: Sun Oct 25, 2015 3:45 pm
Location: Hertfordshire, UK

Re: Maths brainteaser.

No takers then. I think this is called a "bump". 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
Posts: 44
Joined: Sun Oct 25, 2015 9:55 pm

Re: Maths brainteaser.

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

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

55

bindeweede
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Joined: Sun Oct 25, 2015 3:45 pm
Location: Hertfordshire, UK

Re: Maths brainteaser.

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
Posts: 44
Joined: Sun Oct 25, 2015 9:55 pm

Re: Maths brainteaser.

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.