September 10, 2019
Problem of the Week
Tuesday, September 10, 2019
The sequence of triangular numbers begins 1, 3, 6, 10, 15... Find the 20th number in this sequence.
Problem of the Week
Tuesday, September 10, 2019
The sequence of triangular numbers begins 1, 3, 6, 10, 15... Find the 20th number in this sequence.