By using dot (.) patterns, which of the following numbers can be arranged in all the three ways namely a line, a triangle and a rectangle?
A triangle can’t be made by 3 dots, 11 dots or 12 dots and a rectangle can’t be made by 11 dots, hence option A, C and D are incorrect.
A line, a triangle and a rectangle can be drawn by 10 dots as shown,
TRIANGLE:
LINE:
RECTANGLE:
19