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An n × n square of tiles is made. The tiles along the edge form a border. Which rule gives the number of border tiles?

Class 7Formulas and Rules from PatternsAlgebra

A $4 n - 4$
B $4 n + 4$
Cn × n
D $4 n$

Step-by-Step Solution

Each side has

n

tiles, but the 4 corner tiles are counted twice:

4 n - 4

. For the

4 \times 4

square shown: 16 − 4 = 12 border tiles.

Answer: A)

4 n - 4

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