# Figuring point in savings account

1. Feb 9, 2007

### rock4christ

say i have an amount of say \$20000 in my savings account and at 2% interest per month when will I have 1 million?

my current method is 20000(1.02)x=1000000, and solve for x

I get 197, which is months, 197/12=16.4yr. about. is that right?

2. Feb 9, 2007

### Bitter

I guess what you want is a simple compound interestformula

A = P ( 1 + r/n ) ^nt

Amount is equal to princple times 1 plus rate divided by number of times interest is compounded per year to the numbver of times interest is compounded per year times time.

PLug in your values and solve for t

3. Feb 9, 2007

### rock4christ

so 1000000=20000(1+0.02/12)nt what answer would you get?

4. Feb 9, 2007

### Bitter

Not exactly, n would be 6 because your interest is counted every 2 months .

Also, you have to use the n with the exponent too. After that plug and chug and solve for t. You might have to use logs.

5. Feb 9, 2007

### rock4christ

thanks, but i dont know logs yet, im learning them in this unit tho. I was wondering if someone who did know would figure it for me.

6. Feb 10, 2007

### HallsofIvy

Staff Emeritus
Unless it was editted, I don't see where the original post said anything about "every 2 months".

No, that would be for 2% per year and the question is about 2% per month (24% annual- PLEASE tell me where you can get that!). The formula in the orginal post was correct.

$20000(1.02)^x=1000000$
so $1.02^x= 1000000/20000= 50-$, x log(1.02)= log(50),
x= log(50)/log(102)= 198 months, about 16 and a half years, as the original post said. What was all the fuss about?

7. Feb 10, 2007

### Bitter

ah my mistake, I put the 2 from the 2percent in front of the months. It happens.

8. Feb 10, 2007

### rock4christ

I was just seeing if my math was right, and its actually 4% annual, I had a bit of a mix up.