Interest calculation with while

I have no idea where to start for this problem, any help would be appreciated.

Use a while loop to determine how many months it will take to accumulate $1.5 million in your retirement account under the following conditions: initial deposit = $1,000, interest is 0.5%, per month and you pay $750 into the account each month.

Answer 1

[Rani V.S]

 sum=1000
month=0
while sum<1500000
sum=(sum+750)*1.5
month=month+1
end
disp(month)

[Walter Roberson]

That would be 50% interest per month, not 1/2 % interest per month.