So embarrassing but I need help with dd's maths please

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DD is 10 and has been off school after surgery so we've gotten the schoolwork from her teacher that she needs to keep up with but I forget how to do it and she hasn't done them before in school.

I'm so embarrassed, I guess I'm not smarter than a ten year old!

She's been working on fractions and decimals and so far we're doing ok but now we're onto written problems and I have no idea how to teach her.

example: john ate 0.5 of a cake. Mary ate half of what was left. What decimal fraction of the cake remained?

and: I had ?1. I spent 0.1 of it. How much did I spend.

There's 15 of these

I obviously know the answers but how do you write it as a sum?

Please and thank you [very appreciative begging emoticon]

0.1 is 1/10 0.5 is half
so for the first one - john ate half the cake
mary ate half of what was left - the other half (so half of a half is a quarter)
a quarter in decimal fractions is 0.25

Does it specifically say write it as a sum? Can you not just show your working?

so i would write (and im just a mum not a maths guru!)
0.5 (divided by sign) 2 = 0.25

second one

0.1 x £1 = 10 pence

might not be right though!

Hi Sowhat, thank you.

That's the thing, I do know what the answers are but she has to write them down and show in the form of a sum how she actually arrives at the answer and I don't know how to do that.

I vaguely remember moving decimal places from when I was in school but it's been 20 years

She's been doing multiplication of decimals and fractions (changing the fraction to a decimal and she's done some division of figures into figures which have decimals but because these are written in problem form I have no idea how to 'put it in a sum'. I could probably find some outrageous way of arriving at the correct but I imagine there's is a much more simple way that's eluding my ancient brain at the minute and I don't want her going back to school having learned some crazy way to do it.

I have thought of just going into the teacher but I'm just was to embarrassed to ask him

Hi PB, yes she has to write it in a sum.

I'm reading over more of them, they're horrible! I feel so stupid.

1

1 ÷ 2 = 0.5

0.5 ÷ 2 = 0.25

2

1 ÷ 0.1 = 10

Sowhat, I just had a total fit of the giggles. I am imagining you sitting there saying 'for gods sake woman, LOOK!'

She has to do it like ... inside a division box like this l

I think it's moving decimal places or something.

Thank you for trying to educate me but I am obviously far to thick and will have to mortify myself by asking the teacher.

In my view, your daughter and you have done the difficult bit ( ie understanding and being able to do the problem). I wouldn't be embarrassed to say to the teacher "dd can give the answers to these and understands how to do them, but we aren't sure how you want her to set out the working. Can you give us an example layout!"

with the risk of not getting it right again....

2) 1.0
0.5

1) 0.50
0.25

Can you see which bits are meant to be the division box? Tried to get clever and do an underline, but it didnt work!

ps agree with sarahfreck

John ate half of a cake

1/2 = 0.5
1 - 0.5 = 0.5

Mary ate half of what was left

2 into 0.5

2 into 0 doesn't go so write a 0 above it. Put the decimal point in directly above the point 'in the box'.

2 into 5 goes twice with one left over so put a 2 above the 5, then you need to add a 0 after the 0.5 to get 0.50 and put the 'carried' 1 in front of the new 0. 2 into 10 goes five times so put a 5 above the 0 giving an answer of 0.25.

does that make sense? struggling with baby!

For the second one I would say that 0.1 of £1 means 0.1 x 1 = 0.1

(in maths, of means multiply)

but 0.1 isn't money so £0.10 should be the answer or £1 = 100p so 0.1 of 100 is 0.1 x 100 = 10

Depends what they are looking for really and what work has gone before, to give you a clue!

draw a line and chop it into 10 equal pieces - they are tenths (0.1). Take half of them - you will have 5 - (0.1+0.1+ etc = 0.5).

Do it visually until it starts to make sense.

hald of a half is the same as 0.5 x 0.5 = 0.25 or 1/2 x 1/2 = 1/4

0.1 x £1.00 = £0.10(or 1/10 x 100p = 10p)

That kind of thing ?

Hi all, thanks so much for your help. Pan that's the kind of sums she's being doing for the last couple of days so I think it's the closest solution but we've just discovered there is another formula for some of them. converting to fractions, dividing by the bottom and mutiplying by the top.

does this sound right? ...

I had ?1. I spent 0.3 of it. How much money did I spend?
Solution: 0.3 converts to 3/10. Using the box thingy divide 1.00 by 10 and get .10 and then multiply by 3 giving .30 as answer.

yep - that is right - it is just manipulating numbers and realising fractions and decimals are the same thing but decimals are just another way of writing fractions in base 10.

Thanks throckenholt.

Think we're pretty much sorted now. Bloody hell was close to pulling my hair out

Thank you all

not embarrassing at all - had trouble getting my head round that maths myself.