ran a javascript program instead of using math and found that 10,000,001 isn't a triangle number, these are the ones right before and after it:
997578
998991
1000405
1001820
10000001
129 = 10000001
10000001
10000001
10000001 times
28 is a triangle number. The 28th triangle number is 406.
The third triangle number is 6.
The fifth triangle number, known as T5 is 15.
No. Triangle numbers are a fixed set of numbers that can't be altered to make one certain number turn into a triangle number.
The binary representation of the keyword "129" in decimal is 10000001.
A triangular number or triangle number counts the objects that can form an equilateral triangle. 10 objects can be formed into an equilateral triangle.
The area of a triangle can be a rational number or an irrational number depending on its dimensions.