I always found 9 to be easy because whatever you multiply with (2-10) you just had to remove 1 from that number, and maybe memorise the second digit.<p>e.g.<p>9*3 = 3-1 = 2 (+ the 7 that I just memorised)<p>But actually the finger trick is amazing, and I just used it to double check the numbers as it was a loooong time I did it.