The radius of the circle is 4 cm. (The radius is half of the diameter) To find the exact circumference of a circle, you don't multiply by pi. So take off the pi, 2 x 4 = 8
How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)