You should choose the prize that gives you more coins. So you just need to figure out what's worth more, the 50,000 or the final amount of magical coins.
You know that the magical coins double every day. So at the end of 28 days, it will have doubled 28 times (in other words, multiplied by 2, 28 times).
This would be
= <span>268,435,456 (if you just plug it into a calculator).
If you want to show the amount of magical coins you'd have every day, it would look something like this:
</span><span>
<span>
</span><span>
Day
1 (</span></span>
)<span><span> :
2
coins
</span>
<span>
Day
2 </span></span>(
) <span><span>:
4
coins
</span>
<span>
Day
3 </span></span>(
) <span><span>:
8
coins
</span>
<span>
Day
4
:
16
coins
</span>
<span>
Day
5
:
32
coins
</span>
<span>
Day
6
:
64
coins
</span>
<span>
Day
7
:
128
coins
</span>
<span>
Day
8
:
256
coins
</span>
<span>
Day
9
:
512
coins
</span>
<span>
Day
10
:
1,024
coins
</span>
<span>
Day
11
:
2,048
coins
</span>
<span>
Day
12
:
4,096
coins
</span>
<span>
Day
13
:
8,192
coins
</span>
<span>
Day
14
:
16,384
coins
</span>
<span>
Day
15
:
32,768
coins
</span>
<span>
Day
16
:
65,536
coins
</span>
<span>
Day
17
:
131,072
coins
</span>
<span>
Day
18
:
262,144
coins
</span>
<span>
Day
19
:
524,288
coins
</span>
<span>
Day
20
:
1,048,576
coins
</span>
<span>
Day
21
:
2,097,152
coins
</span>
<span>
Day
22
:
4,194,304
coins
</span>
<span>
Day
23
:
8,388,608
coins
</span>
<span>
Day
24
:
16,777,216
coins
</span>
<span>
Day
25
:
33,554,432
coins
</span>
<span>
Day
26
:
67,108,864
coins
</span>
<span>
Day
27
:
134,217,728
coins
</span>
<span>
Day
28
:
268,435,456
coins
So you'd have more with the magical coin. You should pick the magical coin.
</span></span>