9 coins make 10 rows
Make 10 rows with 3 coins in each row, using only 9 coins.
Solution. Let’s take a closer look.
‘X’s represent the coins.
We’ve marked the first three rows in pink.
Fourth row in blue.
Fifth and sixth rows in green.
Seventh and eighth in purple.
Step 8: And the last two rows in red. Ten rows of 3 coins turns out to be possible using only 9 coins!