This puzzle is a standard part of a Professional IQ Intelligence Test, specifically measuring your "Systematic Counting" and "Attention to Detail." Training your brain to categorize information is a powerful form of Brain Fitness that supports Cognitive Health and Healthy Aging.

The secret to solving this is to count the digit 7 in the "Ones place" and the "Tens place" separately:
1. The "Ones" Place (Ending in 7):
Numbers: 7, 17, 27, 37, 47, 57, 67, 77, 87, 97
The digit 7 appears 10 times.
2. The "Tens" Place (Starting with 7):
Numbers: 70, 71, 72, 73, 74, 75, 76, 77, 78, 79
The digit 7 appears 10 times.
3. Watch for the "77" Trap:
The number 77 is special because it has a 7 in both the tens and the ones place. Since we are counting "total appearances" of the digit 7, 77 is counted twice. Our separate counting above already covers both of these 7s.
Final Calculation: 10 (from the ones place) + 10 (from the tens place) = 20 times.

Stay Sharp Tip: Think of this as a mental "filing system." By breaking a large task (counting 1 to 100) into smaller categories (ones vs. tens), you reduce the stress on your brain and improve accuracy. Regular practice with high-quality Intelligence Quizzes like this is a scientifically proven way to maintain mental agility and keep your mind sharp as you age.