I'm not surprised you don't remember something after only learning it 12months though, that isn't very long when you consider you use basic maths right from start to finish to help retain the basics and expand on it. Think how long it takes young children to learn there first language? And they use it day in and day out. I learnt German for almost 8yrs (from age 7 to about 15 and I'm 25 now so 10yrs ago) and even with years in between use am able to rekindle the knowledge very easily when given opportunities to use it. I also learnt Japanese for 2yrs and could only really greet and count now but in 2yrs with a few lessons a week, you do really only learn the basics of a language. In my opinion though it is the process of learning it that is the most important and crucial part; what you remember will only be useful if you need it and if you need it you'll be more likely to remember it anyway.