Friday evenings were always very busy on our smallholding. It was when Father had to get the accounts books made up and ready for the Saturday milk rounds. The two books were put on the kitchen table and before my father came in from cleaning out the dairy my siblings and I were expected to work out the weekly bills for those people who had quite straightforward bills; for example seven pints or seven half pints. There were no calculators in the 1950s, just mental arithmetic. I enjoyed maths then and was encouraged to work hard at it.

When dad had finished his outdoor jobs he would quickly check our calculations and then get on to the complicated bills. Like those who had bought eggs, cream and butter from the van. The mental arithmetic we learnt then was very good practice for us in later life.

I remember when we had moved to a larger farm and dad had travelling salesmen visiting he could calculate how much fertiliser a field needed in his head. He used to say to the young men "put that calculator away – I can work out the amount needed in my head". He was always correct too. He may have had little formal education but his mental maths was excellent.

After having my own family I went to university to study maths and education on a four-year Honours degree, and worked as a maths teacher for almost 20 years at a large comprehensive school. Even with that education and practice I was never a patch on my dad when it came to mental maths.