Question

12 21 23 32 34 43 what is the next numbers

Answer 1

after each number you had 11

so when you subtract

32-12 = 11

now add this 11 to 43

11+43 = 54

so the next numbers are 45 and 54

I hope that's help ! Please let me know if you have questions !

Answer 2

45, because every other number goes up by 9 and ever other number goes up by 2 
12 +9 = 21 + 2 = 23 +9 =32 +2 = 34 +9 =43 +2 =45