Home Forum Chat Forum How many 10s in 868?

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• How many 10s in 868?
• miketually
Subscriber

Not sure it is, a leaf diagram seems to have little or no use in real life, beyond passing your GCSE maths exam.

They make mode and median a bit more obvious, when you’re learning what they are.

D0NK
Subscriber

Mrs just told me about leaf diagrams I never did don’t remember doing them at GCSE/A level.

Back to an earlier point maths is supposed to involve accepted standards so everyone* knows what you are talking about, hence precedence and naming numbers correctly. twentysix hundred should be fairly easy for most to figure out but threesixty, seventwenty and teneighty, which I’m sure most of the people here could guess at, may not mean a lot to a doddery old maths teacher.

….I think

*or atleast everyone who knows/remembers the rules

mogrim
Member

They make mode and median a bit more obvious, when you’re learning what they are.

Suppose so 😕

Wonder if my kids will learn about them? Thanks to the wonders of STW I’m now perfectly positioned to explain it, even in base 1 if need be.

mogrim
Member

Back to an earlier point maths is supposed to involve accepted standards so everyone* knows what you are talking about, hence precedence and naming numbers correctly. twentysix hundred should be fairly easy for most to figure out but threesixty, seventwenty and teneighty, which I’m sure most of the people here could guess at, may not mean a lot to a doddery old maths teacher.

I think you’re mixing up two concepts – mathematical rules (BODMAS and the like), and mathematical culture (how you talk about maths). The first is universal, the second quite clearly isn’t, with some variation even within a country.

GrahamS
Subscriber

Incidentally..

I get the feeling a lot of people on this thread haven’t realised that maths teaching has moved on since they were kids!

Lattice Multiplication was a bit of a revelation for me when I found it recently during an idle browse of Khan Academy.

I was never taught it in school (that I remember), but it seems like a good method of multiplying very large numbers.

jamiea
Member

Do schools give out to parents the syllabus or teaching material? As has been said, it’s all about context, that needs to be conveyed to the parents. It strikes me that when our little girl goes to school there’ll be a whole lot of re-learning to be done!

Cheers,
Jamie

Cougar
Subscriber

Lattice Multiplication

Just googled that as I’ve never come across it before. Unless I’m misunderstanding what I’m seeing, it’s just long multiplication, only with more writing. I guess how I can see how it might simplify multiplication but at the expense of both brevity and comprehension.

That is to say, you can see the logic in long multiplication fairly readily, you’re multiplying by each digit in turn, adjusting for units, and adding them all up. Lattice multiplication looks like a magic trick.

GrahamS
Subscriber

Yep. Try it with a few worked examples though Cougar – bundling the multiply and addition steps together turns it into a much more mechanical task and makes it a lot simpler to do.

The logic is still there – it just takes a bit to adjust your brain to the “columns” being on the diagonals.

jfletch
Member

So “How many tenths of 1.5 are there in 1.5?” means “How many 0.15 are there in 1.5”

And guess what, there are 10 0.15s in 1.5. So the answer is 10. The given answer.

They are testing you know what a tenth, or an eighth or a fith is. The important bit of the question is the “how many tenths” bit. The rest of the question is irelevant, it could be 1.5 or cake or horses or overweight mountain bikers, it doesn’t matter, if you split something into tenths there will always be 10 bits.

You are confusing yourself with your ability to work out what 1 tenth of 1.5 is (and one tenth of 1 if you want to answer 15).

GrahamS
Subscriber

They are testing you know what a tenth, or an eighth or a fith is.

I’m really not convinced they were.

Certainly not in the context of a set of questions about hundreds, tens, and units, (and tenths, hundreths etc).

That just seems to be what someone on Mumsnet decided.

You are confusing yourself with your ability to work out what 1 tenth of 1.5 is (and one tenth of 1 if you want to answer 15).

Nope.

The answer I expected was 5

e.g. simply the contents of the “tenths” column

miketually
Subscriber

They are testing you know what a tenth, or an eighth or a fith is.

They’re not. It’s almost certainly a place value question, so they want to know students can identify which digit represent the tenths. There are two digits, the first shows how many units, the second how many tenths.

jfletch
Member

That just seems to be what someone on Mumsnet decided.

Well there is no way I’m serching Mum’s net to find out.

Cougar
Subscriber

They are testing you know what a tenth, or an eighth or a fith is.

You really think that, at KS2, ie primary school level, ie 7-11 year olds, a valid and sensible way of testing whether a pupil knows how many tenths there are in a whole \$something is to phrase the question as “how many tenths are there in 1.5?” and to expect the answer “10”?

Really?

molgrips
Subscriber

threesixty, seventwenty and teneighty, which I’m sure most of the people here could guess at, may not mean a lot to a doddery old maths teacher.

Unless you’re French, as I learned back in ten nine hundred four twenties and eleven.

D0NK
Subscriber

I think you’re mixing up two concepts – mathematical rules (BODMAS and the like), and mathematical culture (how you talk about maths)

possibly, tho I do wonder if “twelve hundred” is an Americanism, “three sixty” I’m pretty sure is slang, but yeah I could be talking cobblers.

unless you’re French

hmm 21=twenty and one, yeah different countries do numbers differently, fair enough, but surely there is still a national standard? would a French maths teacher kick off if you said “une mille neuf cent neuf dix et une” ? Coz if my 20 odd year old cmel French is right both are 1991 it’s just that yours is correct and mine is merely describing the number. Kinda like 1,200 and twelve hundred.

D0NK
Subscriber

They are testing you know what a tenth, or an eighth or a fith is.

are we sure, is this thread second or third hand, what was the exact wording of the question, what was the answer and was it on the same test as the 868 question? seems weird that they would have a place value question followed by a dubiously simplistic question like that.

GrahamS
Subscriber

seems weird that they would have a place value question followed by a dubiously simplistic question like that

Especially if they used the same language and wording for both questions, making it impossible to tell what the question is asking!

(Which is why I’m pretty sure it is a place value question too)

konabunny
Member

It’s mathematics – the correct answer shouldn’t be different depending on the assumed knowledge of the student.

On the contrary – Ten is a defined term in the context of the exercise. It is also an exercise in critical reading.

batfink
Member

Oooo, oooo! I found a relevant meme:

That’s all

Doug
Member

OK, so if it’s hundreds, tens and units, what is the name of the place value of the first number after a decimal point called if it’s not tenths.

molgrips
Subscriber

would a French maths teacher kick off if you said “une mille neuf cent neuf dix et une” ?

Actually.. mille neuf cent quatre-vingt onze sounds right so maybe you can do both.

In Welsh incidentally there’s a traditional vigesimal (20 based, sort of like the French) counting system but they’ve introduced a decimal system where 13 is un deg tri (one ten three) and 37 is tri deg saith, and it’s strict without any irregularities. Must make teaching hundreds tens and units nice and easy 🙂

GrahamS
Subscriber

In Welsh incidentally there’s a traditional vigesimal

jamiea
Member

possibly, tho I do wonder if “twelve hundred” is an Americanism, “three sixty” I’m pretty sure is slang, but yeah I could be talking cobblers.

My Grandma used to confuse me when telling someone the time. She said 25 past as “five and twenty a’ter“!

Cheers,
Jamie

GrahamS
Subscriber

She said 25 past as “five and twenty a’ter”!

See also KJV Bible: “The days of our years are threescore years and ten”

D0NK
Subscriber

She said 25 past as “five and twenty a’ter”!

As molgrips mentioned, leftovers from quasi vigesimal system? A score is still used now.

With the exceptions of (whole) bike weights and height I’ve always dealt with/thought in the decimal system, thinking about counting in other systems/units/base always seems a bit of a head ****.

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