Question

What is the average of all three-digit numbers divisible by 23?

• A. 752
• B. 552
• C. 652
• D. 452

Answer 1

Answer:

B. 552

The three-digit numbers divisible by 23 form an arithmetic progression.

• Smallest three-digit multiple of 23:
  $23 \times 5 = 115$
  

• Largest three-digit multiple of 23:
  $23 \times 43 = 989$

For any arithmetic progression, the average of all terms is:

• $\text{Average}=\frac{\text{first term}+\text{last term}}{2}$

$\text{Average}=\frac{115+989}{2}$
$=\frac{1104}{2}$
$=552$

Answer: 552 ✅