There are 4 tens in 640 or 640/10 = 64
There are 640 acres in a section.
640 grams = 22.57ounces.
640 ounces = 40 pounds
640 ÷ 8 = 80.
10.6667 minutes in 640 seconds.
640 acres = 27,878,400ft²
640 inches=16.25600 meters
640/24 = 26.67 days
Depens how wide the 640 miles are.
640 milliliters is 0.64 liters.
640/4 = 160