Well done with the Newspaper challenge, we got loads of pieces brought in for the lesson today and were able to produce some excellent work. Well done to those like LW and IG who used the blog to comment their findings.

This week I want you to practise your adding skills by completing one of the challenges on the document linked below. Choose you challenge, but make sure it is a challenge.

maths-challenges

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NA's Dad

October 5, 2008 at 5:32 pm

Hello, We are struggling with finding the ways to make 200 from the 4 digits. I have found the answer on the web, but have not shown NA. I could sit down and find the answer but NA & I have sat down for quite a while to work out how to do it by logic and also choosing random digits & locations. I have worked out that there are 122 possible solutions, using ‘permatations/comibinations’.

Is NA supposed to just plough through 122 sets of 4 two digit sums ?

Any help or advice would be much appreciated.

From Wikipedia :-

* Factorials are used in combinatorics. For example, there are n! different ways of arranging n distinct objects in a sequence. (The arrangements are called permutations.) And the number of ways one can choose k objects from among a given set of n objects (the number of combinations), is given by the so-called binomial coefficient

{n\choose k}={n!\over k!(n-k)!}.

mrcobbsclass

October 5, 2008 at 5:47 pm

Thanks NA’s Dad,

No, he doesn’t need to plough through all those possibilities – the solution I have has 22 possibles. I realise its a tricky one, but I wanted them to practise their addition skills as revised last week. I was not necessarily expecting a single correct answer, just to use the problem for practise. As a tip one solution is using the numbers 1 9 on the top row and 7 2 on the bottom. Giving the sum 19+72+17+92=200

Does that help?

LH's mum

October 5, 2008 at 10:35 pm

We have so far worked out that 1 x top right + 1 x bottom left + 2 x bottom right needs to add up to either 10 or 20. From that, you can then work out what the number in the top left needs to be.

LH

October 6, 2008 at 7:31 pm

First I tried to work out the problem randomly (9x) then I tried it according to a pattern.I have found 10 possibilities but I would like to hear the other 12 MR COBB!

SK

October 7, 2008 at 6:48 pm

I found out that there is a good way of doing this. I used only one even number and three odd numbers. I found three ways of doing this. I got quite additicted and didn’t want to stop!

RK

October 7, 2008 at 7:03 pm

The homework was really hard, but in the end I found 3 different ways to do it. There is a pattern where you have to have an even number either in the top left corner or bottom right of the grid.