Question

for 30 days on the 1st daY I GET A PENNY THAN ON IT DUOBLES EVERY DAY UNTIL DAY 30
HOW MUCH PENNIES DO I HAVE ON DAY30

Answer 1

just take a look at the number of pennies on day #n
n #
1 1
2 2
3 4
4 8
...
n 2^(n-1)

so, on day 30 you have 2^29 pennies
That's about $5.4 million. You could retire and spend the rest of your life counting them!

Answer 2

1000000000