What is the 15th triangular number?
Category: Math · Difficulty: expert
Hint: Use the formula n(n + 1)/2.
Answer
120
Explanation
For the 15th triangular number: 15(16)/2 = 120.
This is a expert math riddle — one of the harder riddles here. The answer is 120.
More Math riddles
- I can be true or false, but I always reveal a conclusion. What am I?
- I can tell you how many, but I cannot hold anything. What am I?
- I can take you to new levels, but I require you to know the right combination. What am I?
- I can be less than one, yet I hold great power. What am I?
- I am constant yet can vary, my components add up, but I’m never in a hurry. What am I?
- I am the backbone of mathematics, allowing for structure and order. Without me, chaos reigns, and…
- I can be odd or even, but I always follow rules. What am I?
- I am a mathematical operation that takes two numbers and gives you a single result. What am I?