Question

What kind of figure does the number 15 show in triangular representation?

(a) Triangular form with base 5

(b) Triangular form with base 4

(c) Triangular form with base 3

(d) Triangular form with peak 1

I had been asked this question by my school principal while I was bunking the class.

Origin of the question is Patterns in Squares of Numbers topic in section Squares and Square Roots of Mathematics – Class 8

Answer 1

Correct answer is (a) Triangular form with base 5

The best explanation: Triangular numbers are the numbers which form a triangle when arranged in increasing form. When the number 15 is arranged in increasing form the base of the triangle has 5 dots, which goes on decreasing and reaches the peak upto 1.