A rod is 16 1/2 feet. A chain is 66 feet of 4 rods. A link is 1/100 of a chain or 7.92 inches. A mile is 320 rods, 80 chains or 5,280 feet.
To reduce square feet to acres .000023 is the reciprocal of 43,560 square feet. Multiply the number of square feet by .000023, or multiply by 23 and count off six places.
A square rod is 272 1/4 square feet. An acre contains 43,560 square feet. An acre contains 160 square rods. An arce is about 208 3/4 feet square. An acre is 8 rods wide by 20 rods long - or any two numbers (of rods) whose product is 160.