Some beads were used to create the figures .
- How many beads were used to create Figure 20?
- A pattern is formed with 345 beads. Which figure would it be?
(a)
Pattern for the number of beads
Figure 1: (1 - 1) x 4 + 1 = 1
Figure 2: (2 - 1) x 4 + 1 = 5
Figure 3: (3 - 1) x 4 + 1 = 9
Formula
Number of beads = (Figure number - 1) x 4 + 1
Number of beads for Figure 20
= (20 - 1) x 4 + 1
= 77
(b)
Figure number with 345 beads
= (345 - 1) ÷ 4 + 1
= 344 ÷ 4 + 1
= 87
Answer(s): (a) 77; (b) 87