Has Maths Changed?

[JohnG]

Helping No3 grandson with his maths and came across an anomaly . . . .let me explain, using simplified numbers

 

What is the answer to this sum? 2+3×4

When I was at school and in my house today, its 24 . . . 2+3 = 6 and 6x4 = 24

 

Nope

According to No3 grandson, the answer is 14 . . . 3x4 = 12 and 12+2 =14

It's "BIG Maths" they 'x' before they '+'.

I was taught that 2+(3x4) = 14

The brackets change the priority.

 

How can maths be changed?

How can we have 2 answers to a single mathematical sum and have agreement in the workspace?

[ianc]

The rule is (and I'm older than you!)

BOMDAS

Brackets Of Moltiply Divide Add Subract

Your grandson is correct.

Ian Cornish

[RogerH]

Hi JOhn

 

You actually introduced another error

you say that 2+3 = 6      but you multiplied them  2+3 = 5

So the school incorrect way of doing it is 2+3     x4 = 20

But the correct way  is 2 + 3x4    14    BODMAS (as Ian pointed out)

 

Roger

Edited May 26, 2024 by RogerH

[david ferry]

Sorry John.

It's always been the BODMAS order. You need to go back to school, taking the rest of your household with you. Hopefully, your grandson will make you all a packed lunch!

Being serious for a moment, you are anything but alone with your incorrect understanding (apart from on here, of course!). It's a very common misunderstanding.

David

[RobH]

 It's worth remembering that M and D have the same importance as do A and S .    The order that you do M and D makes no difference so BODMAS or BOMDAS are both right - but A and S can catch you out if you follow them by rote :

  "2-3+4" ... the answer is 3, not -5 as BODMAS would give.  In a straight sum like that you just work from left to right. 

[JohnG]

25 minutes ago, RobH said:

 

  "2-3+4" ... the answer is 3, not -5 as BODMAS would give.  In a straight sum like that you just work from left to right. 

Ignoring my dunce like example, working from left to right is the way I was taught, the exception being where  bracketed section always takes priority.

 

I wa given this very simple example;

If you have a table, set for 4 people, with each setting being 2 knives and 3 forks, 1 Place setting is 5 pieces

4 settings is 20 pieces

2+3 = 5

5x4 = 20

2+3x4

 

Here  2+ (3x4) doesn't work

 There are 20 pieces on the table

BIG maths is wrong

Or am I missing something

 

[RobH]

You are missing the fact that you have to write the expression properly in the first place John. 

It should be written 2 x 4 + 3 x4  which does work with BODMAS.  It can  be rationalised to   (2+3) x4   but you must include the brackets.

 

 

Edited May 26, 2024 by RobH

[JohnG]

51 minutes ago, RobH said:

You are missing the fact that you have to write the expression properly in the first place John. 

It should be written 2 x 4 + 3 x4  which does work with BODMAS.  It can  be rationalised to   (2+3) x4   but you must include the brackets.

 

 

 

And that's my point

No brackets

The sum is 2+3x4

The sum us simple

You add 2 to 3 and multiply the answer by four

IF there are brackets then the whole sum changes, but, how on earth can 2+3x4 be the same as 2+(3x4) or 2x4+3?

The sum is NOT 2x4+3, it is not 2+(3x4)

The sum is 2+3x4

[RobH]

No John 2+3x4 is NOT the sum. You have truncated it incorrectly without using brackets as you must to do that.  The sum is 2 x 4 + 3 x 4.  

You can't get the right answer if you don't state the problem correctly. 

In your own words. "You add 2 to 3 and multiply the answer by four" so to write that in arithmetical terms you have to separate the two halves of the process using brackets. 

 

Edited May 26, 2024 by RobH

[ianc]

I have always included brackets in order not to be confused (or to confuse others) when handling strings such as this.

In other words, make it absolutely clear how to handle the BOMDAS/BODMAS.

Ian Cornish

[TorontoTim]

BEDMAS here in Canada. Brackets; Exponents; Division; Multiplication; Addition; Subtraction.

If you follow that it's clear. 

My Mum was a maths teacher (in England) and as I remember it always taught to do multiplication (or division) before addition (or subtraction). 

[Ian Vincent]

I think you are outnumbered John. 

Rgds Ian

PS I agree with the BODMAS brigade. 

[BlueTR3A-5EKT]

My grandson has an app for that 

[stillp]

+1 for BODMAs!

Pete

[peejay4A]

Cue Noddy Holder:

”iiiiiit’s BEDMAS”

 

 

Too early?

[Pete E]

Reminded me of the counting the digits on the hands, on one hand count backwards 10,9,8,7,6 then add the 5 from the other hand = 11 

Pete

[cp25616]

Have to say I agree with John G here. I started off thinking what was so difficult with a simple adding and multiplication task? Crickey I am confused now! Thank God they didn't make simple arithmetic out to be so complicated in my day. I'm with you John.

Alan G

[Steve-B]

Dad was an aerospace engineer at the Lockheed Skunk Works in the 60s and early 70s. When I was a young lad struggling with Maths he "helped me" and we both felt that I'd improved dramatically, until I turned in first assignment and got an "F" (fail). Turns out the way he was taught Maths in the 40s and 50s != how it was taught in the early 70s.

#whodathunkit ???

[stuart]

1 hour ago, Steve-B said:

Dad was an aerospace engineer at the Lockheed Skunk Works in the 60s and early 70s. When I was a young lad struggling with Maths he "helped me" and we both felt that I'd improved dramatically, until I turned in first assignment and got an "F" (fail). Turns out the way he was taught Maths in the 40s and 50s != how it was taught in the early 70s.

#whodathunkit ???

So he would have worked on the Blackbird SR71 then?

Stuart.

[Steve-B]

Just now, stuart said:

So he would have worked on the Blackbird SR71 then?

Stuart.

Yep he was was on the B-58 Hustler and then hired to work in the team that designed the YF-12a which became one of the varients of the SR-71. Also worked on the F-111 along the way. Somewhere I've got a photo of him standing with the '71 & '111 at Duxford in the American hangar hall. Dad partially lost his hearing on the '12a due to the long hours in the Ames wind tunnel at Moffet Field..

[stuart]

36 minutes ago, Steve-B said:

Yep he was was on the B-58 Hustler and then hired to work in the team that designed the YF-12a which became one of the varients of the SR-71. Also worked on the F-111 along the way. Somewhere I've got a photo of him standing with the '71 & '111 at Duxford in the American hangar hall. Dad partially lost his hearing on the '12a due to the long hours in the Ames wind tunnel at Moffet Field..

He would know Butch Sheffield then, one of the pilots, his daughter Linda posts interesting snippets about those planes on Twitter @Habubrats.

Stuart.

[Steve-B]

4 hours ago, stuart said:

He would know Butch Sheffield then, one of the pilots, his daughter Linda posts interesting snippets about those planes on Twitter @Habubrats.

Stuart.

No doubt he could’ve. Sadly he’s been gone for 10 years. I used to hollow Haburats on instagram for a while as I don’t Twitter.