18. Higher Order Thinking Some Native American tribes made jewelry with Dentalia shells. Each Dentalia shell is about 1.5 inches long. About how much longer would a necklace made with 24 shells be than a necklace made with 18 shells? Use compatible numbers.

Step 1 ：Given that each Dentalia shell is about 1.5 inches long.

Step 2 ：Calculate the length of a necklace made with 18 shells: \(18 \times 1.5 = 27\) inches.

Step 3 ：Calculate the length of a necklace made with 24 shells: \(24 \times 1.5 = 36\) inches.

Step 4 ：Find the difference in length between the two necklaces: \(36 - 27 = 9\) inches.

Step 5 ：Final Answer: The necklace made with 24 shells would be \(\boxed{9}\) inches longer than the necklace made with 18 shells.