Each of the figures is made up of 1-cm chopsticks.
The table shows the number of chopsticks used to make the figures and their perimeters.

1. Find the number of chopsticks in Figure 13.
2. What is the perimeter of Figure 197?
3. Which figure requires a total number of 1999 chopsticks?

(a)
Pattern for the number of chopsticks
Figure 1: 1 x 8 + 7 = 15
Figure 2: 2 x 8 + 7 = 23
Figure 3: 3 x 8 + 7 = 31

Formula:
Number of chopsticks = Pattern number x 8 + 7

Number of chopsticks in Figure 13
= 13 x 8 + 7
= 111

(b)
Pattern for the perimeter of the figure
Figure 1 = 1 x 2 + 7 = 9
Figure 2 = 2 x 2 + 7 = 11
Figure 3 = 3 x 2 + 7 = 13

Formula:
Perimeter of the figure = Pattern number x 2 + 7

Perimeter of figure 197
= 197 x 2 + 7
= 401

(c)
Figure number x 8 + 7 = 1999
Figure number x 8 = 1999 - 7 = 1992
Figure number = 1992 ÷ 8 = 249

Answer(s): (a) 111; (b) 401; (c) 249