If you put one dollar a day in the bank and earn 20 percent interest per month, how much would you have in 100 years

Very silly question, but ....

amount = 1(1.2)^1200
= 1.041 x 10^95

that is 1041000000....0000 for 96 digits

(we don't even have "names" for a number like this.
There is nothing measureable requiring that number.
The number of atoms in our visible universe is estimated at 10^85 or so )

actually, since a googol is 10^100, this is just

10.41 microgoogols

To calculate the amount of money you would have in 100 years by putting one dollar a day in the bank with a 20 percent interest rate per month, you would follow these steps:

1. Determine the total number of days in 100 years:
There are 365 days in a year, so in 100 years, there are 100 * 365 = 36,500 days.

2. Calculate the monthly interest rate:
Divide the annual interest rate (20%) by 12 to get the monthly interest rate: 20% / 12 = 1.67%.

3. Calculate the total amount accumulated each month:
Since you are depositing one dollar each day, you will accumulate 1 dollar * 30 (assuming an average of 30 days per month) = 30 dollars each month.

4. Calculate the total amount after each month:
Add the accumulated amount from step 3 to the previous month's total, and add the interest earned from that total. For the first month, the starting amount is 1 dollar. The formula for each subsequent month is:
Total amount after month X = (previous total + accumulated amount + interest for previous month)

Repeat this calculation for each month of the 100 years, 36,500 times.

5. Calculate the final amount after 100 years:
After performing the calculations for all 36,500 months, you will have accumulated a final amount after 100 years.

Please note that performing this calculation manually is quite complex and time-consuming due to the large number of iterations. Using a spreadsheet or a programming language would significantly simplify the process.