...anyway, yes I can remember this book now...I had loved it...we were each given at copy...at about 13 years old...sue, deb and I...we were then quizzed on the different problems, afterwards...go figure...

remember sue and the log books in that O' level class?..."but that's not how you do it..."

https://books.google.co.uk/books?id=CAWtAAAAMAAJ&pg=PA258&lpg=PA258&dq=what+does+2M19+mean&source=bl&ots=mdUWoy7j44&sig=p6SP1q1dNUBa6d6aALGihZQPJw8&hl=en&sa=X&ved=0ahUKEwjVwuyY5c7NAhUJJsAKHZ6RByAQ6AEINzAG#v=onepage&q=what%20does%202M19%20mean&f=false