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Maths question help

(11 Posts)
Gileswithachainsaw Wed 26-Apr-17 20:22:48

I know the answer however I need to know what method/how to explain how to get the answer appropriate for a yr 5

Tom thinks of a number

He adds half the number to a quarter of the number and makes 60

How would you teach a 10 yr old how to figure it out. As my method is probably no good grin

PurpleDaisies Wed 26-Apr-17 20:24:34

If he adds half of the number to a quarter of the number, he's made three quarters of the number.

If the knows what three quarters is, he can work out one quarter, and then the whole number.

Gileswithachainsaw Wed 26-Apr-17 20:26:47

See i just divided by three then times by four

I was just checking tht there wasn't supposed to be some kinda x+y =z thing that yr 5s start being taught about now and we were missing the point smile

CarrotCakeMuffins Wed 26-Apr-17 20:27:33

Use Algebra. Where a is Tom's number.
So 1/2 a + 1/4 a = 60
3/4 a = 60
a = 80
Assuming I've understood the question right.
Hope that helps

CarrotCakeMuffins Wed 26-Apr-17 20:28:41

Dd has done a bit of algebra in yr 6 but not sure about year 5

Gileswithachainsaw Wed 26-Apr-17 20:30:16

I will check with dd

As marks are also giving for workings I just wanted to check that we hadn't missed something

Thanks smile

Ginmakesitallok Wed 26-Apr-17 20:30:44

I'd go with carrot cakes explanation.

senua Wed 26-Apr-17 20:35:12

I agree with carrot. I think the main thing to teach is:
accept that you don't know the answer yet and that is OK.
we'll invent a thingy to call this unknown ('a' in carrot's workings)
convert the words into Mathematical symbols
don't panic
follow mathematical logic and it all falls into place
simplessmile

Gileswithachainsaw Wed 26-Apr-17 20:36:12

Thanks everyone smile

Seems I was kinda right minus the algebra grin

PurpleDaisies Wed 26-Apr-17 20:37:30

I don't think that most year 5s will be able to do that algebraically. They are used to doing problems based around adding fractions and finding a whole number if you know half/a quarter etc.

cantkeepawayforever Wed 26-Apr-17 21:12:43

A year 5 might be more familiar with this as an 'empty box' problem (these are introduced from really early years, with the box standing for the unknown - so even a Y1 or Y2 child would be familiar with e.g. 3 + [] = 10, the number in the empty box must be 7).

So they might say
half a number plus quarter of a number is three quarters of a number.
So 3/4 of [] (empty box) = 60
One quarter of [] = 60 divided by 3 = 20
If 20 is 1/4 of the number, the whole number must be 20 x 4 = 80

Children might not always work through the steps after the 3/4 of [] = 60 numerically as I have shown. Some might draw a diagram in which they show 3/4 of a whole, label the 3/4 60 and then spot that each 1/4 must be 20 so the whole is 80. others might sport the relationship between 6 and 60, and use their knowledge that 6 is 3/4 of 8 to say that 60 is 3/4 of 80, or embark on some trial and improvement.

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