an wrote...
I have next cells:
A B C D
101 1 3

With =A1 & C1 & D1, I obtained 10113.
However, I need to intercalate one string type 001, 002...
between cells.

Example:
A B C D
101 001 1 3
(Where 001 is formated with Custom to have 3 digits.
I would like to obtain 10100113.)
....

An alternative,

=SUMPRODUCT(A2:D2,{1000000,100,10,1})