Things should be as simple as possible, but no simpler

The title of today's Blog is a quote from Einstein.

I was roundly reminded of it last night when I tried to help my 8 year old with his numeracy homework, which I have reproduced below!

If you wish, have a go at it yourself before reading on

My error was classic, I was thinking far too deeply about the problem. I read the question and was instantly mesmerised by the term 'addition square'.

I dived straight into Google sorted out the difference between 'addition squares' and 'magic squares', decided that these were not magic squares and delved deeply into 'addition squares'.

But then, there was something wrong, In all the examples, there was another set of figures to the right of each row, and below each column. In some examples all these numbers were present, in others, some were missing.

Should the bottom row and right hand column be these external figures?
Had the teacher forgotten to include them?
Had my son been verbally given these values and forgotten?
Was there an error in the publication?

I told my son not to worry about it, there was an error in the question which made it impossible to answer, so he should forget it!

But I do like to cover all my bases, and put the puzzle on Facebook with an appeal.

Within minutes, James was the first to mail me the answer, Thank you James.

The problem was so so simple.

Add the number in the left hand column to the number at the top of the row, and put the answer where the two intersect. So 5 + 9 = 14, the 14 goes immediately below the 9. Using the same mechanism, 18 goes below 13. Now the last row is already filled in for us, 35, but the number at the top of the column is missing. 5 + what = 35? 30 of course, so that goes in the top right hand square.

I am continually repeating to the attendees on my course - the simple approach is always the best - go for the simple method first.

And I fell into that very same trap.

The lesson ?

Never be complacent, there is always value in refresher courses, even if it is just to bring you back down to earth!