Answer:
15,729 = (1 x 10000) + (5 x 1000) + (7 x 100) + (2 x 10) + (9 x 1)
1/2 of 24 = 12
To write a number in expanded notation, you add the highest digit plus the next highest digit plus the next highest digit and so on.
To figure out 1/2 of 24, you divide 24 by 2 and your answer comes out to be 12.
Hope this helps! :))