Since decimalisation, place value to two places of decimals has become easy. Everyone knows that 1p is not much or 10p either these days, though it is of course better than 1p, which you might not bother to pick up. A pound has become the unit, and everyone knows that £10 is a lot and £100 a great amount. So, we work to two decimal places all the time, and HMI have quite rightly commended money as a way of teaching place value. Children understand it.
But move from this to putting figures on paper, and we have a different problem. The range of problems that children have as they do this, and the errors they make, encompass virtually any way you can think of to get something wrong . I have personal experience of this. In my Year 7 arithmetic exam, I interpreted my father's advice that it was more important to show your working than to get the right answer, by carefully and neatly writing out every single sum and then not actually doing any of them. It took a concerned visit from a parent to persuade the school that I really could add up. They, alas, then took that too literally by putting me in a top set, doing work I could not understand (in geometry. I understood it in my thirties). This propensity to get things wrong has, my piano teacher tells me, been very valuable to me as a teacher, as it enables me to understand my pupils' problems. The poor man has to think of something positive to say. My wife sympathises with him.
Well, I've hit on the idea that the sums involved in arithmetic to two places of decimals are not that difficult, provided children know their tables, and so I spend a great deal of time teaching these and practising them. But then the problem seems not so much to be in the maths, which are often based on single digits, but in losing track of the sum, losing your place, leaving out a step, forgetting to put in a 0, etc. Pupil in Y8 (with statement for dyslexia, in my view unjustifiably) is prone to these errors, and I've developed for him a series of steps for division which I've posted below and which he finds helpful
French ruled paper (a sample here) helps him to keep on track better than anything else. The main squares are big, so his largeish figures don't throw him out of track with columns, and the series of steps and improving tables mean that he is beginning to handle division by a single digit to two places of decimals accurately. Rounding up was a problem though. P understood that you rounded up the second digit, or left it untouched. He did not, though, delete the third placed digit. Another small step, quite a lot of practice, and he'd got it by the end of our session. Maybe doing things like that myself helped me to understand how other people do them, and to adapt the explanation accordingly.
French ruled paper is equally useful for helping people with weak handwriting - the feint narrow lines between the main squares are very good for establishing consistent size in the body of letters.