Question

Find the sum of the first 30 positive multiples of 3.

Answer 1

3 + 6 + 9 + 12 + 15 + 18 + 21 + 24 + 25 + 28 + 32 + 36 + 39 + 42 + 45 + 48 + 51 + 54 + 57 + 60 + 63 + 66 + 69 + 72 + 75 + 78 + 81 + 84 + 87 + 90 = x

Answer 2

^^^ long / lazy way

Answer 3

\[\Large\rm 3+3\cdot2+3\cdot3+3\cdot4+...+3\cdot30\]Factoring a 3 out of each term:\[\Large\rm 3\left[1+2+3+4+...+30\right]\]You can write this as a summation if it helps:\[\Large\rm 3\sum_{n=1}^{30}n\]

Answer 4

ya. like what @zepdrix just did is the better way

Answer 5

Is the answer 1,395 ?

Answer 6

let me check really quick

Answer 7

yes it is

Answer 8

Thank you!

Answer 9

Sure thing