What is the rule of the product of two adjacent natural numbers What's the rule of the product of two adjacent natural numbers?

What is the rule of the product of two adjacent natural numbers What's the rule of the product of two adjacent natural numbers?

Because only individual digits are considered, the product of adjacent natural numbers 1 × 2 = 2,2 × 3 = 6,3 × 4 = 12,4 × 5 = 20,5 × 6 = 30,6 × 7 = 42,7 × 8 = 56,8 × 9 = 72,9 × 10 = 90,10 × 11 = 110 can only be 0,2,6