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

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