The task is to complete the calculation using the given digit cards (1, 3, 9, 4, 5). You may use each digit more than once, and the goal is to investigate possibilities if the final answer is a 4-digit number.

Let’s break this down step by step:

Observations

1. Structure:

   • The calculation involves multiplying a two-digit number by a one-digit number.
   • The partial product in the middle ends in 5, and the second partial product ends in 0.
   • The total result starts with 8, indicating a 4-digit product.

2. Available digits:

   • You can use 1, 3, 9, 4, and 5 for any digit in the calculation.

Plan

1. Determine which two-digit numbers multiplied by a one-digit number yield a 4-digit product starting with 8.
2. Ensure that partial products align with the 5 and 0 endings as shown in the grid.

Let’s calculate!

Step 1: Setting up possibilities

We will denote:

• The two-digit number as AB (where A and B are digits from the cards).
• The one-digit multiplier as C (a digit from the cards).

The product AB × C must satisfy:

• The result is a 4-digit number starting with 8.
• The partial products fit the grid constraints.

Step 2: Testing combinations

Let me compute some possibilities! Possible digits from the card digits = [1, 3, 9, 4, 5]

Conditions to satisfy:

- AB (2-digit number) * C (1-digit number) -> a 4-digit number starting with 8

- Intermediate products fit the grid constraints

Store valid combinations

results = []

Iterate over all possible two-digit numbers (AB) and single digits (C)

for A in digits: for B in digits: if A != 0: # Ensure AB is a valid 2-digit number AB = 10 * A + B for C in digits: product = AB * C if 8000 <= product < 9000: # Check if it's a 4-digit number starting with 8 # Check intermediate product constraints partial_1 = (AB % 10) * C # Units digit * C partial_2 = (AB // 10) * C # Tens digit * C if partial_1 % 10 == 5 and partial_2 % 10 == 0: results.append((AB, C, product))

resultsNo combinations using the given digits (1, 3, 9, 4, 5) satisfy all the conditions provided in the problem (result starts with 8, and partial products align with the grid constraints). This might indicate additional clarification is needed for the problem setup or constraints.

Let’s revisit the constraints or attempt a refined approach to find a solution. Do you want me to focus on adjusting the constraints or solving in an alternate manner?