May 4, 2023
A triangular number makes a triangle. You get them by adding the numbers in order.
1 = 1
1 + 2 = 3
1 + 2 + 3 = 6
1 + 2 + 3 + 4 = 10
How can you find out if a triangular number is even if they only gave you the number? I’ll tell you.
If you want to, find out the pattern ODD ODD EVEN EVEN. So now you want to know which ones are even? Well, if you can divide the number by 4 that it means it’s an even triangular number. Or if the number is below a number than can be divided by 4 then it is also even.
For example, the first triangular number is odd because you can’t divide 1 by four. The second number is odd because you can’t divide 2 by four. But the third triangular number is even because 3 is below a number than can be divided by four. And the fourth triangular number is even because 4 can be divided by four.
Number Triangular Number
1 1 Odd
2 3 Odd
3 6 Even
4 10 Even
5 15 Odd
6 21 Odd
7 28 Even
8 36 Even
9 45 Odd
10 55 Odd
11 66 Even
12 78 Even
13 91 Odd
14 105 Odd
15 120 Even
16 136 Even
