Table:
0
A
B
C
D
E
1
order item id
order id
product id
product quantity
other order item details
2
1
4
4
6
3
2
4
10
7
4
3
15
5
4
5
4
1
3
9
6
5
2
14
3
7
6
13
12
8
8
7
1
15
3
9
8
10
4
4
10
9
14
5
1
11
10
13
9
2
12
11
15
7
5
13
12
4
14
4
14
13
12
13
1
15
14
13
14
2
16
15
13
14
6

Questions and formulas:
Question: Display all order IDs
Formula: UNIQUE(B1)
Formula2: UNIQUE(B2:B16)
Level: easy
Question: How many order items does each order have?
Formula: SUMMARIZE(B1,SUMX(A1))
Formula2: SUMMARIZE(B2:B16,SUMX(A2:A16))
Level: easy
Question: How many times has each product been ordered? 
Formula: SUMMARIZE(C1,SUMX(B1))
Formula2: SUMMARIZE(C2:C16,SUMX(B2:B16))
Level: easy
Question: How many orders of each product?
Formula: SUMMARIZE(C1,SUMX(B1))
Formula2: SUMMARIZE(C2:C16,SUMX(B2:B16))
Level: easy
Question: How many products in each order? 
Formula: SUMMARIZE(B1,SUMX(C1))
Formula2: SUMMARIZE(B2:B16,SUMX(C2:C16))
Level: easy
Question: number of products bought in each order
Formula: SUMMARIZE(B1,SUMX(C1))
Formula2: SUMMARIZE(B2:B16,SUMX(C2:C16))
Level: easy
Question: What's the total product quantity for each order?
Formula: SUMMARIZE(B1,SUMX(D1))
Formula2: SUMMARIZE(B2:B16,SUMX(D2:D16))
Level: easy
Question: What are the ids of orders?
Formula: UNIQUE(B1)
Formula2: UNIQUE(B2:B16)
Level: easy
Question: How many orders for different products?
Formula: SUMMARIZE(C1,DCOUNTX(B1))
Formula2: SUMMARIZE(C2:C16,DCOUNTX(B2:B16))
Level: easy
Question: Number of products ordered by each order.
Formula: SORT(SUMMARIZE(B1,SUMX(C1)), 1, 1)
Formula2: SORT(SUMMARIZE(B2:B16,SUMX(C2:C16)), 1, 1)
Level: medium
Question: the number of products for each order
Formula: SUMMARIZE(B1,SUMX(C1))
Formula2: SUMMARIZE(B2:B16,SUMX(C2:C16))
Level: easy