Looks like a place to practice mental arithmetic tricks, you know, like multiplication by 11:

  11 × 16 = 1(1+6)6
  34 × 11 = 3(3+4)4
  124 × 11 = 1(1+2)(2+4)4

Or multiplication table 10 through 20:

  14 × 17 = (14+7) × 10 + 7 × 4
  13 × 18 = (13+8) × 10 + 8 × 3