Maths question

[Drukk]

Wonder if anyone could assist with the two questions below, I can work these out with trial and error but does anyone know an actual method to solve them? These are a couple of questions my 10 year old is stuck on and I'm really not sure in this instance what the method is, google also failed me!

......._12.2_
....._______
1_ /819_.00


..... _40
....____
_4/57_0

Both are partially complete division questions and need the missing digits marked by the _ symbol, ignore the lines of dots, for some reason spaces would not register so had to use dots to get the rows to line up correctly.

 

[Drukk]

OP, try using [ code ] tags (minus spaces, obvs) as it's fixed width. I assume you are going for something like this:

      _12.2_
    ________
1_ / 819_.00


      _40
    _____
_4 / 57_0

That is exactly it, thanks for laying it out better than I managed.

 

[Drukk]

I wouldn't call this maths as much as I would call it Applied Guessing. For example, taking the second one first, I can see that the last number of the divisor is 4 and the last numbers of the result are 40. So whatever the original number that was divided into probably ends with 60. (Because 4 * 40 = 160). So I plug in a 6 in the lower right blank to give me 5760 in the lower part. I then try a couple of sample numbers for the divisor. First I try 14, but that doesn't give me a whole number. So then I try 24 and I find 5760/24 = 240. I can fill in 2 for the top blank now. And I thus end up with the following:

      240
      ___
24 | 5760

Don't feel bad about not getting this. There isn't (so far as I know) a simple mathematical way of doing this. Just guessing and using common sense (like I did above) to rule out the number of guesses to try.

Honestly, I'm not very impressed if this is what we're asking ten year olds to do now. I suppose it checks that they know how to actually do division because they need to do it to check their guesses, but it's not really teaching them much other than if you don't know the answer, try guessing. :/

Or does anyone else have some insight which I've missed?

Thanks for the explanation, I was thinking along the same lines in that it is all just trial and error, this seems pretty hard for 10 year old kids. My lad can do division using bus stop method or chunking but this I think is a little bit tough for them at that age. I suppose you could class it as reasoning but even so, that is not easy. I am seeing his maths teacher later this week anyway on a parents evening so will ask what it is all about then.