@penTlak learning the 1–99 × 1–9 multiplication tables is medium-difficult, but for sure means you can shortcut through a lot of small mental calculations.
Firstly, consider why you want to know them. If it’s just for a party trick or a memory challenge, then feel free to use standard mnemonic techniques.
If you want to use them in other calculations, you need to have the result directly, and mnenomic techniques won’t be suitable for this due to the demand on visual working memory. You might use them initially, but ultimately you will have to train to shortcut any mnemonic techniques.
Some things that might help you:
- Start with the most useful and simplest times tables first (e.g. 24, 51, 99).
- Look for patterns within the data (e.g. 3 × 37, 6 × 37, 9 × 74 etc. fall in a pattern; the 99-times table is also easy).
- Regardless of whether you use mnemonics, palaces, patterns, or none of these, the last part of your training would be to use some flashcard system to ensure you can answer any of these multiplications in less than about 1.5 seconds (including typing). I have made such a tool for my personal training and for my students, although originally I used to use Anki.