Find a pattern, then fill in the next two numbers: 0, 1, 5, 14, 30, ____, ____
Hint
Try arithmetic and exponential.
Answer
Add the next square number: + 12, + 22, + 32, + 42. The next two numbers are 55 and 91.
Example 2
A triangle has no diagonals, while a quadrilateral has 2, a pentagon has 5, and a hexagon has 9. Without drawing the figure, how many diagonals will a septagon (7-sided figure) have?
Hint
Make a chart of the sides and the diagonals.
Answer
The pattern is +2, +3 +4, +5. A septagon has 14 diagonals.
