How do I remove a space from the middle of a line of numbers?

[Raich]

I have a list of mobile numbers as 07777 123456 and need them to be
07777123456. How do I do this?

 

[Allllen]

if your phone number is in cell b4 then use this
=SUBSTITUTE(B4," ","")

 

[Sloth]

you can also use the find/replace feature. Enter a space in the find box,
and nothing in the replace box. This way you don't need a helper column.