To remember things, you need to create visualizations. One tool to assist with that is the 'major memory system' for remembering numbers. This was popularized by Jerry Lucas and Harry Loraine in their Memory book. I use this for difficult numbers to remember, it works quite well. One difficulty with it, though, is that it's sometimes hard to think of a word that goes with the letters. But it's worth the effort to think of one, the thought process also puts more focus on the thing you are trying to remember.