Table:
0
A
B
C
D
E
F
G
H
1
transaction id
account id
invoice number
transaction type
transaction date
transaction amount
transaction comment
other transaction details
2
1
13
12
Payment
3/15/2018 21:13
613.96
3
2
9
1
Payment
3/13/2018 13:27
368.46
4
3
6
1
Refund
3/3/2018 1:50
1598.25
5
4
9
12
Payment
3/10/2018 13:46
540.73
6
5
9
2
Payment
3/23/2018 4:56
1214.22
7
6
12
3
Refund
3/22/2018 21:58
1903.41
8
7
13
14
Payment
3/12/2018 3:06
1585.03
9
8
14
15
Payment
3/11/2018 21:57
1425.41
10
9
8
12
Payment
3/7/2018 4:32
1517.77
11
10
6
15
Payment
3/14/2018 19:09
1477.57
12
11
6
13
Refund
3/12/2018 22:51
1567.64
13
12
9
6
Refund
3/5/2018 19:55
1781.24
14
13
13
12
Refund
3/24/2018 12:05
899.87
15
14
11
5
Refund
3/13/2018 3:51
1462.62
16
15
4
14
Refund
2/27/2018 14:58
1979.66

Questions and formulas:
Question: Number of completed transactions
Formula: SUM(A1)
Formula2: SUM(A2:A16)
Level: easy
Question: How many transactions have we recorded? 
Formula: SUM(A1)
Formula2: SUM(A2:A16)
Level: easy
Question: How many transactions were recorded in each account?
Formula: SUMMARIZE(B1,SUMX(A1))
Formula2: SUMMARIZE(B2:B16,SUMX(A2:A16))
Level: easy
Question: How many transactions under each type?
Formula: SUMMARIZE(D1,SUMX(A1))
Formula2: SUMMARIZE(D2:D16,SUMX(A2:A16))
Level: easy
Question: total transactions for each type.
Formula: SUMMARIZE(D1,SUMX(A1))
Formula2: SUMMARIZE(D2:D16,SUMX(A2:A16))
Level: easy
Question: Which account has the most recorded transactions?
Formula: TAKE(SORT(SUMMARIZE(B1,SUMX(A1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(B2:B16,SUMX(A2:A16)), 2, -1), 1)
Level: hard
Question: How many transactions realized?
Formula: SUM(A1)
Formula2: SUM(A2:A16)
Level: easy
Question: How many transactions?
Formula: SUM(A1)
Formula2: SUM(A2:A16)
Level: easy
Question: The total transaction amount under each type.
Formula: SUMMARIZE(D1,SUMX(F1))
Formula2: SUMMARIZE(D2:D16,SUMX(F2:F16))
Level: easy
Question: The account with most records of transaction
Formula: TAKE(SORT(SUMMARIZE(B1,SUMX(A1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(B2:B16,SUMX(A2:A16)), 2, -1), 1)
Level: hard