Good for additon? Yes!

Good for MULTIPLICATION? YES!

Here's how. Begin by numbering your fingers of both hands 6, 7, 8, 9, 10.

Now work out 7x8:

Join fingers 7 and 8. Count the total number of fingers at the join and below. Here there are 5. So take 5x10=50. Count the number of fingers on the left hand above the join and in the right hand above the join. Here we have 3 and 2. So take 3x2

ANSWER 5x10 + 3x2 = 56

How does it work?

Take axb, with a and b between 6 and 10, and get
((a-5)+(b-5))x10 + (10-a)x(10-b) = axb!