Question

find the 10th triangular number​

Answer 1

Answer:

55, 66, 78, 91, 105, 120

Step-by-step explanation:

Answer 2

So, the 10th triangular number is 10 + 10 + 10 + 10 + 5 + 10. Another interesting way of adding

the numbers is to add the first and the last, then the second and the second to last, and so on.

This leads to (1+ 10) + (2 + 9) + (3+ 8) + (4 + 7) +

(5 + 6). This simplifies to 11 + 11 + 11 + 11 + 11 = 55.