Does this work for you?
1. First of all, pick the number of days a
week that you would like to eat out or do anything fun.
2. Multiply this number by 2.
3. Add 5.
4. Multiply it by 50.
5. If you have already had your birthday this year add 1749. If you haven't, add 1748.
6. Last step: Subtract the four digit year that you were born.
You should now have a three digit number:
The first digit of this was your original number (i.e. how many times you want to eat out each week). The second two digits are your age!!!
1999 is the only year it will ever work, so spread the fun around while it lasts...