Option one
Option one is quite straightforward, as you can do this formula:
Number of days in month x 10 = amount of money recived
Also in February option 1 is better than option 2 by £7.
And if pocket money stopped on day 8 option one would give you £80, option 2 £38 and option 3 only £2.55.
Option two
To work out how much you would receive here, I used Microsoft Excel to
create the pattern of plus 0.5 (50p) which gave me this:3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
13.5
14
14.5
15
15.5
16
16.5
17
17.5
18
with a total of £325.50.
Option 3
I used a calculator and Microsoft Excel to double 0.01 (1p), with a result of:0.01
0.02
0.04
0.08
0.16
0.32
0.64
1.28
2.56
5.12
10.24
20.48
40.96
81.92
163.84
327.68
655.36
1310.72
2621.44
5242.88
10485.76
20971.52
41943.04
83886.08
167772.16
335544.32
671088.64
1342177.28
2684354.56
5368709.12
10737418.24
You become a millionaire on day 28, and on day 15 it becomes the most fruitful. I had a total of £21474836.47.