(ii) US$10,000 (63,000 yuan) iTunes gift card (exact figure)
25 billion apps downloaded (approximated figure)
(iii) the amount of money must be given as an exact number if not the person reciving it will be surprised when he/her gets the gift card and finds out that it is not the amount of money that he had expected
the amount of apps downloaded are too many as it is almost a billion apps so it has to be rounde of if not the munber will be very long.
(iv) i think that the numbers have been rounded of to 10 million,