What is the missing digit in 2220 * so that the number becomes a perfect square?

The missing digit is 1.

Finding the Missing Digit

According to the reference provided, we need to find a digit to replace the asterisk () in 2220 such that the resulting number is a perfect square. Here's how we can approach this:

1. Understanding Perfect Squares: A perfect square is a number that can be obtained by squaring an integer (e.g., 16 is a perfect square because 4 * 4 = 16).

2. Estimation: The reference states that the largest possible perfect square near 22200 is 22209.

3. Square Root: We know from the reference that the square root of 22209 is slightly more than 149. This suggests that the perfect square is close to 149 squared.

4. Calculation: We calculate 149² which equals 22201. This confirms that 22201 is a perfect square and very close to 2220*, so we know what the missing digit is.

5. Verification:

• 149 * 149 = 22201
• 150 * 150 = 22500

Therefore, the perfect square closest to 2220* that fits the pattern is 22201.

Conclusion

Based on the provided information and calculations, the missing digit in 2220* that makes the number a perfect square is 1.