Evaluate the sum of common logs: log 10(10) + log 10(100) + log 10(1000) + log 10(10000) + log 10(100000).

Introduction / Context:
This is a direct application of the definition of common logarithms on powers of 10, where log 10(10^k) = k.

Given Data / Assumptions:

• Numbers: 10, 100, 1000, 10000, 100000 (i.e., 10^1 to 10^5)
• Base 10 logarithms.

Concept / Approach:
Use log 10(10^k) = k and add the results.

Step-by-Step Solution:

Verification / Alternative check:
No alternative needed; the identity is exact for powers of 10.

Why Other Options Are Wrong:
Expressions like log 11111 or 14·log 100 do not equal the integer sum of the exponents here; only 15 matches.

Common Pitfalls:
None significant; just ensure all logs are base 10 and recognize each term as a power of 10.

Final Answer:
15