On the event of new year each student of class XI sends cards to his classmates. If there are 40 students in the class number of cards exchanged during the process is

Options

A. 1200
B. 600
C. 780
D. 1560

Answer

To solve the problem of how many cards are exchanged among 40 students in a class where each student sends a card to every other student, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**: Each student in the class sends a card to every other student. Therefore, if there are 40 students, we need to determine how many cards are sent in total.

2. **Calculating Cards Sent by One Student**: Each student sends a card to 39 other students (since they do not send a card to themselves).

\[ \text{Cards sent by one student} = 39 \]

3. **Calculating Total Cards Sent by All Students**: Since there are 40 students, the total number of cards sent can be calculated by multiplying the number of cards sent by one student by the total number of students.

\[ \text{Total cards exchanged} = 40 \times 39 \]

4. **Performing the Multiplication**: Now, we perform the multiplication to find the total number of cards exchanged.

\[ 40 \times 39 = 1560 \]

5. **Conclusion**: Therefore, the total number of cards exchanged during the process is 1560.

### Final Answer:
The total number of cards exchanged is **1560**.

---