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Yes, the number 21 is indeed a triangular number. Other triangular numbers are 6,10, and 15.
Wiki User
∙ 8y ago
Wiki User
∙ 12y agoYes
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What is the 6th triangular number?
21
How do you find the 20Th triangular number?
The 20th triangular number is 20*21/2 = 210
Is 32 a triangular number?
32 is not a triangular number. The first few triangular numbers are 1, 3, 6, 10, 15, 21, 28, 36, 45, ...
How can sixth triangular number be 21?
Because it is ! The first 10 triangular numbers are... 1,3,6,10,15,21,28,36,45 & 55
Is 23 a triangle number?
No, 23 is not a triangular number. Here are a few examples of triangular numbers: 21, 28, 55, 45, 78 and 91.
What is the 6th triangular number?
21
How do you find the 20Th triangular number?
The 20th triangular number is 20*21/2 = 210
If 10 is the 4Th triangular number what is the 6Th?
21
Is 32 a triangular number?
32 is not a triangular number. The first few triangular numbers are 1, 3, 6, 10, 15, 21, 28, 36, 45, ...
How can sixth triangular number be 21?
Because it is ! The first 10 triangular numbers are... 1,3,6,10,15,21,28,36,45 & 55
If the eighth triangular number is 36 what is the seventh trianguler number?
28"21" but to be extra smart the answer is "The seventh triangular number is twenty one."
Is 23 a triangle number?
No, 23 is not a triangular number. Here are a few examples of triangular numbers: 21, 28, 55, 45, 78 and 91.
Is 8 triangular number?
No. The first few triangular numbers are 1, 3, 6, 10, 15, 21, 28, ...
Which number between 20 and 40 is both a triangular number and a square number 36 or 25 or 21 or 35?
36 is the only square number that is also a triangular number between 20 and 40.
Is 47 a triangular number?
47 is not a triangular number. Triangular numbers less than 100 are 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, and 91.
What triangular number has 4 factors?
6, 10, 15, 21, 55, 91...
What triangular numbers are equal to the sum of two other triangular numbers?
Thre are infinitely many solutions. The smalest set with two different triangular number adding to another is 6 + 15 = 21
