Zhangzidao Town, Changhai County, Liaoning Province has installed a hands-free marble telephone that can be used. The diameter of each key on the phone is 15cm. How many square centimeters is the area of each button larger than the area of the cup mouth with a diameter of 1dm? (Numbers are reserved as integers)

R = 15÷2 = 7.5(cm)R = 1× 10÷2s = 3. 14×(7.5？ -5? )

= 10÷2 =3. 14×(56.25-25)

=5 (square centimeter) =3. 14×3 1.25

≈ 98cm2

Answer: The area of each button is 98 square centimeters larger than a teacup with a diameter of 1dm.