A Christmas tree has ornaments in a pattern. Row 1 has 1 ornament, row 2 has 3, row 3 has 6, row 4 has 10. How many ornaments are in row 5?

Question

Accepted Answer

15 ornaments. The pattern adds consecutive integers: 1, 1+2=3, 3+3=6, 6+4=10, 10+5=15. These are triangular numbers.

Ornament Pattern