This rectangle has a perimeter of 25 units. What is the length of the longer side

What is the number 321,000,000 in scientific notation? also what is the number? ?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

What is the best estimate of the length of a football