what age child would you say for these sums?

[lukeskywalker]

1+1=2
2+2=4
4+4=8
8+8=16
16+16=32
......... more
512+512=1,024
..........more
32,768+32,768=65,536
...........more
1,048,576+1,048,576=2,097,152
to do them in your head with no working out on paper & in the space of about 15 minutes?
thanks

I have a child in my Y1 class who can double numbers into the thousands in his head probably wouldn't get into the millions but I've not tried.

Able year 4?

My DS could have done them in y1 too but he's not 'normal' in terms of what he SHOULD be capable of doing.

At a guess I'd say an average y4 should be capable of doing it though

wow that was fast, thanks for the quick response.

The child in my class isn't particularly good at maths but is good at dooubling.

My reception age ds4 can do doubling but I don't know how high up he can go.

Ds2 was doing all sorts of sums in his head from a young age and would have been more than able in yr one. He is good at maths, but doubling on its own is simplish.

Ds3 can do maths but prefers to write it down whereas ds2 is very good at mental maths and does it all in his head.

Ds2 in y1 has got to 4294967296 (32nd power of 2) in a particularly dull assembly on healthy eating.

Aaaaaaaargh one of my twin boys(year4) has been bombarding me with this for over a couple of years,drives me crackers.

For an 'average' child probably around y4.

For MN children...definitely preschool!

My brother could do them all age 4. But he is a maths freak ;)

My dd1 is yr1, is seen as reasonable able at maths and could do up to 16.

I think as soon as they learnt to add number like this:

`12
+12
=24

These doubling should not cause problem for them. Because they just picture the 2 numbers under each other in their mind and add together those digits that is under each other.
But I do not know which year they are doing this in the school.

It depends on how they're taught and practiced. They can be learned like a chant or times table and if you learn them that way age is irrelevant.

I couldn't get all that way mentally tbh and I am pretty adept with numbers. I need to write things down to keep it in my mind.
DS in year 4 would have a good go and he's ok at Maths. DD in year 2 would get a bit discouraged (especially if DS was doing it).

I can't really see the point of doubling numbers that large mentally - I go happily up to 8,192 but after that need pencil and paper :)

If the child was doubling not those numbers but any random number a passing stranger cared to throw at him then I'd say wow!

DS1 could have done these in year 3, however mental arithmetic is his favourite thing.

Ask him at the same time to spell arithmetic and he would have been stumped.

Hi Lukeskywalker

If you haven't discovered it - although still draft - here is the proposed National curriculum for mathematics KS1 - 2. media.education.gov.uk/assets/files/pdf/d/draft%20national%20curriculum%20for%20mathematics%20key%20stages%201%202.pdf

Adding to 20 in your head: definitely a skill by end of KS1 (Y2) at most schools currently

Draft curriculum: target for end Y1: recall and use number bonds and related subtraction facts within 20 p 4 of 28. By end Y2: rapidly recall and use addition and subtraction facts to 20 p. 7 of 28.

This concept is expanded for Y2 as: Ensure pupils practise [yes - their spelling error - although I shan't cast stones] addition and subtraction of number bonds to 20 so that they become fluent in recalling them. This includes using related facts to perform calculations (e.g. using 3 + 7 = 10, 10 - 7 = 3 and 10 ? 3 = 7 to calculate 30 + 70 = 100, 100 - 70 = 30 and 100 ? 30 = 70). p 7 of 28.

So this would imply starting to get some of what you are suggesting - 16 + 16 etc....

But again this may depend on both facility with numbers, recognition of place value (units, tens, hundreds, thousands) and strong working memory.

I can see most Y2 pupils getting the deconstruction of 16 + 16 as equivalent to 10 +10 and 6 + 6 or 20 + 12 which could either go straight to 32 or may need the additional step of 20 + 10 = 30 and then +2.

Once this deconstruction of units, tens, hundreds, etc... is solid then children can indeed work with facility to solve fairly large calculations (addition or subtraction).

Whether this occurs though is another question.

For my DD1 (Y5) - no problem. For DD2 (Y3) - certainly o.k. to hundreds and maybe could do simple 1,000s - like adding 1200 + 1500.

Draft national curriculum has Y2 (P7 of 28)

Add and subtract numbers mentally including:
- a 2-digit number and ones
- a 2-digit number and tens
- two 2-digit numbers

With target for end of Y3 (p. 11 of 28) stating:

accurately add and subtract numbers mentally including: pairs of one- and 2-digit numbers; 3-digit numbers and ones; 3-digit numbers and tens; 3-digit numbers and hundreds & the note suggests these mental calculations should have answers "exceeding 100".

--

Although I do understand that most problems presented to DDs at school are always set out horizontally (e.g. 2999 + 366 = ), to be honest at some stage using a piece of paper and writing the problem vertically just is easier.

15 minutes seems too long for these
1+1, 2+2, 4+4

I think most can do those by end of reception (my reception DS can't)

8+8=16
16+16=32

end of y1

......... more
512+512=1,024

end y2

..........more
32,768+32,768=65,536

yr2-4

...........more
1,048,576+1,048,576=2,097,152

Some will manage in y3, others will find it too tough in y6

It should be practise, shouldn't it?

Practise is correct :)

Practise with an s is the verb and practice with a c is the noun. Unless you're in America when both have a c

Thanks Quangle & MirandaWest - thanks - have to say that was a new one on me (but I am from US originally) - have been here 22 years and missed it though.

Not sure if your ** comment was directed at me or not Quangle. Point I'm trying to make is that latter bit of the list (as mental maths) isn't identified specifically in proposed national curriculum and seems a bit tricky for say Y2 (in 15 minutes) - and frankly a lot of my DD1's Y5 class would struggle (but our school has issues mathematically speaking).

seems lljkk broadly agrees.

In think Quangle meant that her nit picking about whether a word should have an s or a c was ignoring the actual content of the thread (am also guilty as charged).

It was me missing the point pastsellbydate

I just didn't have anything useful to contribute on the maths questions b