**1**row of one coin using that

**1**coin.

How many coins are needed for rows of two coins? The answer is 3: put the coins in a triangle and you make **3** rows of two coins using **3** coins.

PART 1

Now, how many coins are needed to make as many rows of 3 as there are coins?

PART 2

If that was easy, how many for 4?

Note: if you are making rows of 4, any line drawn can intersect with a maximum of 4 coins. (you cannot place 5 coins in row and count it as two rows of 4) And no stacking coins.