The diagram shows the pattern for the number of circles.
- How many circles will Pattern 6 contain?
- How many circles will Pattern 36 contain?
- Which pattern contains 871 circles?
(a)
Pattern for the number of circles
Figure 1: 1
2 + 1 + 1 = 3
Figure 2: 2
2 + 2 + 1 = 7
Figure 3: 3
2 + 3 + 1 = 13
Formula
Number of circles = Figure number
2 + Figure number + 1
Figure 6: 6
2 + 6 + 1 = 43
(b)
Number of circles in Figure 36
= 36
2 + 36 + 1
= 1296 + 36 + 1
= 1333
(c)
Guess & Check
Figure number
2 + Figure number + 1 = 871
29
2 + 29 + 1 = 871
Figure 29 contains 871 circles.
Answer(s): (a) 43; (b) 1333; (c) 29