能帮我详细解答这道题吗?---**Extracted Content:** **Question Stem:** 曾经有一家餐馆，店号“天然居”，里面有一副著名对联：客上天然居，居然天上客。巧得很，这副对联恰好能构成一个乘法算式：_______。“天然居”表示成三位数是______。 **Mathematical Layout Description:** A vertical multiplication problem is shown below the text. The top row represents the multiplicand, a five-digit number formed by the characters 客 上 天 然 居, labeled with place values 万 (ten thousand), 千 (thousand), 百 (hundred), 十 (ten), 个 (unit) from left to right. The second row shows the multiplier, which is the digit 4, aligned under the units place of the multiplicand. A multiplication symbol (x) is to the left of the multiplier. A horizontal line separates the multiplicand and multiplier from the product. The bottom row represents the product, a five-digit number formed by the characters 居 然 天 上 客, aligned below the horizontal line by place value. The implied mathematical equation is: (客 上 天 然 居) × 4 = (居 然 天 上 客) where each character represents a unique digit from 0 to 9. **Derived Information (Solution based on the puzzle):** Solving the cryptarithmetic puzzle (客 上 天 然 居) × 4 = (居 然 天 上 客) reveals the mapping: 客 = 2 上 = 1 天 = 9 然 = 7 居 = 8 The question asks for the three-digit number represented by "天然居". Based on the derived mapping: 天 = 9 然 = 7 居 = 8 The three-digit number is formed by these digits in the order 天然居, which is 978.