Question 1: Calculate 7,856 - 4,379 using multiple exchanges. Show your steps.

Answer: 3,477

Question 2: Subtract 12,045 from 20,639. Demonstrate the process with multiple exchanges.

Answer: 8,594

Question 3: Perform 15,732 - 9,584 step by step, explaining each exchange.

Answer: 6,148

Question 1: A bookstore has 18,245 books. After selling 6,789 books, they receive a new shipment of 4,563 books. How many books are now in the store? Show your detailed calculation.

Answer: 15,999

Question 2: A factory produces 45,678 units in January. In February, production drops by 12,345 units. In March, it increases by 4,567 units. What is the total production after March? Explain your steps.

Answer: 37,907

Question 1: A student has $2,345. She spends $1,278 on books and $463 on supplies. How much money does she have left? Show your working.

Answer: 604

Question 2: A farmer has 12,500 liters of water. He uses 3,475 liters for irrigation, then receives a delivery of 2,150 liters. How much water does he have now?

Answer: 11,175

Question 1: Calculate 25,489 - 16,278, where multiple exchanges are needed. Explain each step clearly.

Answer: 9,211

Question 2: A school has 48,736 pages of books. They lend out 13,459 pages and then receive 2,385 pages in return. What is the current total number of pages available? Show your working.

Answer: 37,662

Question 1: A student attempted to subtract 9,876 from 15,432 but incorrectly got 6,546. Identify the mistake in their exchange process and provide the correct steps.

Answer: Error in borrowing from the hundreds place; correct steps involve borrowing 1 from the thousands place, making the hundreds digit 13, then proceeding with subtraction.

Question 2: Subtract 23,456 from 45,789. A student incorrectly borrowed only once in the hundreds place. Explain why this is wrong and show the correct method.

Answer: Incorrect borrowing leads to wrong digits; proper method requires borrowing at each necessary place, especially in the thousands and hundreds.