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.
- Find the number of chopsticks in Figure 15.
- What is the perimeter of Figure 139?
- Which figure requires a total number of 1015 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 15
= 15 x 8 + 7
= 127
(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 139
= 139 x 2 + 7
= 285
(c)
Figure number x 8 + 7 = 1015
Figure number x 8 = 1015 - 7 = 1008
Figure number = 1008 ÷ 8 = 126
Answer(s): (a) 127; (b) 285; (c) 126