wrong flash-fill function in excel

Question

let us suppose that we have following numbers in excel,generally flash fill is used to repeat formatting based on sample of formatting we give to excel, for example we have 6 digit numbers in excel

214567
343001
414571
333211

in excel i wrote following pattern

21-45-67

and used flash fill function to complete others formatting, but i am getting incorrect result

21-45-67
34-30-67
41-45-67
33-32-67

which seems definitely in correct, why?is there any rule or why i am getting wrong result?

Answer 1

When Excel 2013's Flash Fill¹ gets it heuristic guess wrong, supply an addition pattern example. In this case, B2 would be 34-30-01 to supplement B1's 21-45-67 pattern.

        

Now select B1:B4 and run Flash Fill.

        

---

¹ _{The Flash Fill command was introduced with Excel 2013. It is not available in earlier versions.}