using 3.14 for Pi , since you didn't say what value to use
area = PI x r^2
Area of larger circle = 3.14 x 500^2 = 785,000 square units
area of smaller circles = 3.14 x 1^2 = 3.14 square units
785,000/ 3.14 = 250,000 small circles can fit into larger one