๐ Apply: Pine Ridge Trail Run
Jordan is training to run the 28.8-mile Pine Ridge Trail on the path shown below. Hydration and aid stations are placed along the path every 1.6 miles. How many aid station intervals are along the entire trail?
The 2-Step Decimal Rule for Division:
Step A: Move the decimal in the divisor 1 place to the right until it is a whole number.
Step B: Move the decimal in the dividend 1 place to the right to match!
Work Through the Problem: 28.8 รท 1.6
Divide the total trail distance by the distance between stations:
Expression:
28.8 รท 1.6
Look at the divisor 1.6 (the outside number). Move the decimal 1 place to the right ($\times 10$) to make it a whole number:
Because you moved the divisor's decimal 1 place right, you must also move the dividend 28.8 (the inside number) 1 place to the right ($\times 10$):
Now perform standard long division with your new whole-number problem:
Original Problem: $28.8 \div 1.6$
Step 2 (Move Divisor): $1.6 \xrightarrow{\times 10} \mathbf{16}$
Step 3 (Move Dividend): $28.8 \xrightarrow{\times 10} \mathbf{288}$
Step 4 (Divide): $288 \div 16 = \mathbf{18\text{ aid station intervals}}$
Pedagogical Rationale: Separating the divisor shift from the dividend shift teaches students why the change happens: the divisor *must* become a whole number first, and the dividend shifts *to maintain an equivalent ratio* ($\frac{28.8 \times 10}{1.6 \times 10} = \frac{288}{16}$).