Table:
0
A
B
C
D
E
F
1
Number
Name
Type
Builder
Works number
Date built
2
1
Talyllyn
0-4-2 ST
Fletcher,Jennings &Co. , Whitehaven
42
1864
3
2
Dolgoch
0-4-0 WT
Fletcher,Jennings &Co., Whitehaven
63
1866
4
3
Sir Haydn
0-4-2 ST
Hughes, Falcon Works , Loughborough
323
1878
5
4
Edward Thomas
0-4-2 ST
Kerr Stuart , Stoke-on-Trent
4047
1921
6
6
Douglas
0-4-0 WT
Andrew Barclay , Kilmarnock
1431
1918
7
7
Tom Rolt
0-4-2 T
Talyllyn Railway
none given
1991

Questions and formulas:
Question: Who was the Builder for the locomotive that has a works number of 323?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,E1=323),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F7,E2:E7=323),4))
Level: medium