Answer:
See attached
Explanation:
You want the possible arrangements of four places where each place can have a blue square or a red circle.
Number
The number of possibilities is ...
2 × 2 × 2 × 2 = 2⁴ = 16
where 4 is the number of places, 2 the number of values
When all possibilities are exhausted for a given place, then next possibility for the next place to the left is used. This is similar to counting in base 2.
The patterns are shown in the attachment.
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Additional comment
There are a number of counting rules that can be devised. We chose to describe the rule you may be most familiar with. It is similar to the rule you use for counting in base ten.
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