Table:
0
A
B
C
D
E
F
1
engineer id
company id
first name
last name
other details
maintenance engineers
2
1
14
Etha
Reinger
Skilled
3
2
2
Clemens
Orn
4
3
6
Samanta
Hauck
5
4
3
Lorine
Morar
6
5
15
Manley
Grady
7
6
1
Courtney
Adams
8
7
11
Josie
Harvey
Skilled
9
8
9
Nellie
Hirthe
10
9
4
Brian
Stamm
11
10
4
Naomi
Price
12
11
7
Cullen
Kunde
13
12
10
Alexys
Simonis
14
13
2
Weston
Hahn
15
14
11
Jules
Goldner
16
15
3
Archibald
Streich

Questions and formulas:
Question: the last names and engineer ids
Formula: UNIQUE(HSTACK(D1,A1))
Formula2: UNIQUE(HSTACK(D2:D16,A2:A16))
Level: easy