Question

If you have three pennies on January first, six pennies on January 2, nine pennies on January 3, and continue this pattern for one year (not a leap year), what will be the value of your entire savings ,in dollars, at the end of one year? Express your answer as a decimal

Answer 1

$36

Answer 2

You get 3 pennies every month. There are 12 months in a year, so multiply 3 x 12, which equals 36.

Answer 3

There's a convenient trick for adding sums like this: On day k, we're saving 3*k pennies, and we are saving for a total of n days. Then we add the number of pennies saved on the kth day to the number added on the (n-k)th day; you'll see that for all values of k, this will be the same.

Answer 4

so do you set it up with a formula I know that 3 is the difference but I can't remember the formula you use for this

Answer 5

There is no formula, other than what I have provided above:D
"(n-k)" @AnswerMyQuestions has the right answer. Only, if he can show how he got it.

Answer 6

I did

Answer 7

i got the answer 2003.05 o the test it is just that i don't know how to solve it

Answer 8

Whoops. Sorry, AnswerMeQuestions. Didn't even see that. :o