Intelligent Math Puzzle – Challenge 81
Enjoy solving math puzzles and critical thinking challenges? If so, then this challenge is just for you. The answer is also given.

Challenge:
What is the last number in the 18th row in the following pattern?
First row: 2
Second row: 3 4
Third row: 5 6 7
Fourth row: 8 9 10 11
…
A- 169
B- 170
C- 171
D- 172
E- 173
The Absolute Best Book to challenge your Smart Student!

The correct answer is D.
Each row has one number more than the previous row. The first row has one number, the second row has two numbers, and the 18th row has 18 numbers.
To answer the question, we should find the number of numbers in all 18 rows.
\(1 + 2 + 3 + … + 17 + 18 = \frac{18}{2}(1+18) = 171\)
The first number starts with 2. Therefore, the last number is 172 (171 +1).
More math articles
- How to Find Slope From a Graph?
- 10 Most Common 5th Grade NYSE Math Questions
- 3rd Grade MCA Math Worksheets: FREE & Printable
- Sum and Difference of Trigonometric Functions Formulas
- PSAT / NMSQT Math-Test Day Tips
- Praxis Core Math – Test Day Tips
- ISEE Middle Level Math Formulas
- Geometry Puzzle – Challenge 62
- CLEP College Algebra Formulas
- FREE 3rd Grade MAP Math Practice Test
What people say about "Intelligent Math Puzzle - Challenge 81"?
No one replied yet.