Hello, sux@math!

That's not the formula . . . In fact, it's notMeredith starts a saving fund for her son. She deposits $10 on his 1st birthday,

$20 on his 2nd, $30 on his 3rd, and so on for 40 years.

Use . . . . No!anyformula!

The sum of the first n terms of an arithmetic series is:

. .

Now try it with: .