The figure shows a pattern formed using some matchsticks.
- How many matchsticks are used to form 81 squares?
- How many squares can be formed using 241 matchsticks?
(a)
Pattern for the number of matchsticks
1 square: 1 x 3 + 1 = 4
2 squares: 2 x 3 + 1 = 7
3 squares: 3 x 3 + 1 = 10
Formula
Number of matchsticks = Number of squares x 3 + 1
Number of matchsticks for 81 squares
= 81 x 3 + 1
= 244
(b)
Number of squares x 3 + 1 = 241
Number of squares x 3 = 241 - 1
Number of squares = 240 ÷ 3
Number of squares = 80
Answer(s): (a) 244; (b) 80