1. A common multiple is a number, specifically a whole number, that is a shared multiple between 2 or more numbers.
2. Given the information above, we can see there's a list of multiples for 6 and 8. The multiples that 6 and 8 share are 24 and 48, so they're common multiples.
The formula for this is . If the diameter is 8 the radius is 4, so filling in accordingly we have and which is and when you multiply in 3.14 you get that A = 401.92 or B above.