Extract the Numeric Characters from a Text String
The following formula extracts the numeric characters from the text string in A2...
=SUM(MID(0&A2,LARGE(ISNUMBER(--MID(A2,ROW(INDIRECT("1:"&LEN(A2))),1))*
ROW(INDIRECT("1:"&LEN(A2))),ROW(INDIRECT("1:"&LEN(A2))))+1,1)*
10^ROW(INDIRECT("1:"&LEN(A2)))/10)
Note that the formula needs to be confirmed with CONTROL+SHIFT+ENTER. If done correctly, Excel will automatically place curly braces {...} around the formula.
Based on the sample data, the formula returns 123456.
Sample Workbook: Download