Lame ass maths riddle

nyarlothothep

What is 30÷2(2+3)÷5

Is it 15?

or 0.6?
...
Or is this question broken?

hondasam

I Don't understand the question

nyarlothothep

Well what does the equation equal? Or is there something wrong with it?

Isn't it 15?

30 divided by two

equals 15

2 plus three equals 5

15 multiplied by five equals 75

75 divided by five is fifteen.

No? It's been a while since I was in school, but I thought that was the way it worked

Cavehill Red

It's 30 over the 2(2+3) over 5.
So that's 30 divided by (2X5) divided by 5.
Which is 30/10 divided by 5.
Which is 3/5 = 0.6.

JBnaglfar

^^ I got that at first.

If you want to get 15 you can.

2(2+3) divided by 5 = 2
30 divided by 2 = 15.

This is basically asking 30 divided by 10 divided by 5, and I didn't think maths necessarily went from left to right.

Edit: google suggests .6 is correct
link

nyarlothothep

I love troll maths

mari2222

it is 15. to get the answer .6 you would need another set of brackets within the equation.

nyarlothothep

Here's another one

-20=-20
16-36=25-45 (16-36=-20,25-45=-20)
4^2-36 = 5^2-45 (4^2=16,5^2=25)
4^2-36 = 5^2-45
4^2-2.4.9/2 = 5^2-2.5.9/2 (2.4.9/2=36,2.5.9/2=45)
4^2-2.4.9/2 +(9/2)^2 = 5^2-2.5.9/2 +(9/2)^2 (adding both the sides (9/2)^2
[4-(9/2)]^2 = [5-(9/2)]^2 (let 4=a,9/2=b)
4-(9/2) = 5-(9/2)
4 = 5
2+2 = 5

And

10x^2-19x=-6 =?

2cool4school

youve lost me lads

stimpson

http://lmgtfy.com/?q=30%C3%B72(2%2B3)%C3%B75

desertstorm

MoodeRator

nyarlothothep wrote: »

What is 30÷2(2+3)÷5

Is it 15?

or 0.6?
...
Or is this question broken?

30÷2(2+3)÷5
15(5)/5
=15
Maybe or maybe not. But I read it exactly the same as Papa smut

coffee_cake

0.6 - brackets first, then multiplication, then divide left->right

A common technique for remembering the order of operations is the abbreviation "PEMDAS", which is turned into the phrase "Please Excuse My Dear Aunt Sally". It stands for "Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction".

http://www.purplemath.com/modules/orderops.htm

MoodeRator

bluewolf wrote: »

0.6 - brackets first, then multiplication, then divide left->right



http://www.purplemath.com/modules/orderops.htm

I'll just put my hat back on and go stand in my corner again.

Cool Mo D

It's only a riddle if you can't remember primary school maths. Brackets first, then multiplication, then division. There is more than one division, then go left to right, giving 0.6.

MJRS

I thought multiplication and division were equal priority so you just do left to right? Hence the acronym being BOMDAS or BODMAS, both are valid. Isn't this one of loads of maths problems with two provable correct answers?

Got this from the ever reliable wiki "These mnemonics may be misleading,
especially if the user is not aware that
multiplication and division are of equal
precedence, as are addition and subtraction."

Saila

answer = 0.6

onlyrocknroll

0.6

Didn't your teacher teach you about BOMDAS?

edit; oops missed MJRS's post

MARTINOZ

Anyone that got 0.6 needs to go back to primary school.

http://www.google.com.au/search?hl=en&source=hp&biw=1004&bih=610&q=30%2F2%282%2B3%29%2F5+%3D&oq=30%2F2%282%2B3%29%2F5+%3D&aq=f&aqi=&aql=f&gs_sm=e&gs_upl=1391l34015l0l17l17l2l6l0l0l453l2328l2-6.0.2

randombar

Back in my day it was BOMDAS!!

davetherave

2cool4school wrote: »

youve lost me lads

Maybe you should have stayed in school?? ....sorry

It's 0.6.

30÷2(2+3)÷5 brackets first
30÷2(5)÷5 then multiplication
30÷10÷5 then division left to right
3÷5
0.6

28064212

It's 15. The only way it could be 0.6 is if you redefine 5(2+3) to mean (5 * (2+3)) instead of 5 * (2+3). Bracket notation for multiplication is just shorthand, it doesn't change the precedence.

30÷2(2+3)÷5
= 30÷2(5)÷5
= 30÷2*5÷5 (÷ and * have equal precedence and are left-associative, so you do them left-to-right)
= 15*5÷5
= 75÷5
= 15

The bolded part is where most people make their mistake. "Brackets first" means you calculate what is inside the brackets first. when brackets are used for multiplication it is just shorthand for *.

onlyrocknroll

28064212 wrote: »

It's 15. The only way it could be 0.6 is if you redefine 5(2+3) to mean (5 * (2+3)) instead of 5 * (2+3). Bracket notation for multiplication is just shorthand, it doesn't change the precedence.

30÷2(2+3)÷5
= 30÷2(5)÷5
= 30÷2*5÷5 (÷ and * have equal precedence and are left-associative, so you do them left-to-right)
= 15*5÷5
= 75÷5
= 15

The bolded part is where most people make their mistake. "Brackets first" means you calculate what is inside the brackets first. when brackets are used for multiplication it is just shorthand for *.

Damn you, I thought I was right and now I'm confused.

Why have you forsaken me BOMDAS?

im invisible

i dont know, maybe ask in the maths forum?

Mellor

JBnaglfar wrote: »

^^ I got that at first.

If you want to get 15 you can.

2(2+3) divided by 5 = 2
30 divided by 2 = 15.

This is basically asking 30 divided by 10 divided by 5, and I didn't think maths necessarily went from left to right.

Edit: google suggests .6 is correct
link

no it doesn't

http://www.google.ie/search?rlz=1C1DVCP_enIE394IE394&sourceid=chrome&ie=UTF-8&q=30+divided+by+10+divided+by+5#sclient=psy&hl=en&rlz=1C1DVCP_enIE394IE394&source=hp&q=30%C3%B72(2%2B3)%C3%B75&aq=&aqi=&aql=&oq=&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=9838aa61b26af9a1&biw=1312&bih=560

Cool Mo D wrote: »

It's only a riddle if you can't remember primary school maths. Brackets first, then multiplication, then division. There is more than one division, then go left to right, giving 0.6.

davetherave wrote: »

Maybe you should have stayed in school?? ....sorry
It's 0.6.

30÷2(2+3)÷5 brackets first
30÷2(5)÷5 then multiplication
30÷10÷5 then division left to right
3÷5
0.6

LMFAO

Trying to be condesending and end up looking like a fool
You should probably go back to school your self guys

30÷2(2+3)÷5............so brackets first
30÷2(5)÷5................2(5) is a shorthand way of writing 2x5, so lets change that so you don't get confused
30÷2x5÷5..................Multiplication and division arecomplimentary so the order doesn't matter

30x5÷5÷2
30÷5÷2x5 etc all equal 15


Anybody that is getting .6 is obviously dividing 30 by 10
That's the same as dividing by both 2 and 5. Which is obviously wrong as their is no ÷ before the 5.
For that to be the case it would have to read

30÷(2(2+3))÷5 or 30÷2÷(2+3)÷5

martineatworld

I don't know why anyone is being condescending tbh.

According to Mellor's link, Google is putting in an extra pair of brackets to come up with that answer. There's an ambiguity about the structure of the question that leads me to believe that both answers are valid

Which leads to petty squabbles on the internet about who's right given there are two valid ways.

28064212

martineatworld wrote: »

I don't know why anyone is being condescending tbh.

According to Mellor's link, Google is putting in an extra pair of brackets to come up with that answer. There's an ambiguity about the structure of the question that leads me to believe that both answers are valid

Which leads to petty squabbles on the internet about who's right given there are two valid ways.

Google puts in brackets for clarification, it doesn't change the precedence. Put in 6 - 2 * 3 and it will "change" it to 6 - (2 * 3).

The only way there's ambiguity is if you change 2(5) to mean something different to 2 * 5

Mellor

There is only something ambiguous if you make a mistake

ClutchIt

The question is broken really. Even though there is a correct way of doing it, anyone who writes an equation in that fashion is an ignoramus

GT_TDI_150

nyarlothothep wrote: »

What is 30÷2(2+3)÷5

Is it 15?

or 0.6?
...
Or is this question broken?

just saw this,

I thought you first caclulate whats in the brackets -> (2+3) = 5
then you multiply it by 2 -> 2(5)=10
then the 2 divisions are dont in the order they appear sp first 30/10=3
then 3/5=.6

could be well wrong