Question

What Is the next number? 12 21 23 32 34 43

Answer 1

12 21 23 32 34 43
so, we add 11 to 12 and get 23, then we add 11 to 23 and get 34, now we have to add 11 to 34 and get 45, that is the next number:
12 21 23 32 34 43 45 54

Answer 2

the next number is 45.
they have a partner
the partner is 9 and 2