Table:
0
A
B
C
D
E
1
State (class)
Vacator
Reason for change
Successor
Date of successors formal installation
2
Virginia (1)
Vacant
Failure to elect
Isaac S. Pennybacker ( D )
Elected December 3, 1845
3
Massachusetts (2)
Isaac C. Bates ( W )
Died March 16, 1845
John Davis ( W )
Elected March 24, 1845
4
New Hampshire (2)
Benning W. Jenness ( D )
Resigned June 13, 1846 after successor elected
Joseph Cilley ( D )
Elected June 13, 1846
5
South Carolina (3)
George McDuffie ( D )
Resigned August 17, 1846
Andrew Butler ( D )
Elected December 4, 1846
6
Iowa (2)
Iowa admitted to the Union December 28, 1846
Iowa admitted to the Union December 28, 1846
Vacant
Not filled this term
7
Iowa (3)
Iowa admitted to the Union December 28, 1846
Iowa admitted to the Union December 28, 1846
Vacant
Not filled this term
8
Louisiana (2)
Alexander Barrow ( W )
Died December 29, 1846
Pierre Soulé ( D )
Elected January 21, 1847

Questions and formulas:
Question: Name the vacator for failure to elect
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="Failure to elect"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E8,C2:C8="Failure to elect"),2))
Level: medium
Question: Name the state class for  iowa admitted to the union december 28, 1846
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="Iowa admitted to the Union December 28, 1846"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E8,C2:C8="Iowa admitted to the Union December 28, 1846"),1))
Level: medium