The first four triangular numbers 1,3,6 and 10 are illustrated in the diagram. What is the tenth triangular number?
Answer Choices
A. 55
B. 45
C. 66
D. 78
E. 50
The first four triangular numbers 1,3,6 and 10 are illustrated in the diagram. What is the tenth triangular number?
Answer Choices
A. 55
B. 45
C. 66
D. 78
E. 50