Final answer:
To convert 1.8×10⁴ to thousands, we move the decimal four places right to get 18,000 iron pieces, which is equivalent to 18 thousands of pieces used for the Eiffel Tower.
Step-by-step explanation:
The question asks us to convert 1.8×10⁴ from scientific notation to a regular number so we can understand how many thousands of wrought-iron pieces were used in the construction of the Eiffel Tower. To do this, we move the decimal point four places to the right, because the exponent on the 10 is 4, which means we multiply 1.8 by 10,000.
After moving the decimal, we get 18,000 pieces. To express this in thousands, we divide the number by 1,000, leading us to 18 thousands of pieces used in the tower's construction.