1. In Excel, convert the numerical format to "text".

2. Alt + F11 to open the window of Microsoft Visual Basic for Applications.

3. Click "Insert" and choose "Module".

4. Copy and paste the following VBA code:

Sub addbrackets()
Dim Rng As Range
Dim WorkRng As Range
On Error Resume Next
xTitleId = "KutoolsforExcel"
Set WorkRng = Application.Selection
Set WorkRng = Application.InputBox("Range", xTitleId, WorkRng.Address, Type:=8)
For Each Rng In WorkRng
Rng.Value = "(" & Rng.Value & ")"
Next
End Sub

5. Hit F5 to run, click ok (if prompts), and then select "range".

6. If needing to change decimal figures after putting parentheses, type the following:

="("&FIXED(abs(A1),3,FALSE)&")"

(A1 is the the value before, 3 is the number of decimal places.)