wording improvements

Author: atk

exercises/piecing-it-together/introduction.md

@@ -2,5 +2,5 @@
 
 Your best friend has started collecting jigsaw puzzles and wants to build a detailed catalog of their collection — recording information such as the total number of pieces, the number of rows and columns, the number of border and inside pieces, aspect ratio, and puzzle format.
 Even with your powers combined, it takes multiple hours to solve a single jigsaw puzzle with one thousand pieces — and then you still need to count the rows and columns and calculate the remaining numbers manually.
-The even larger puzzles with multiple thousand pieces look quite daunting now.
+The even larger puzzles with thousands of pieces look quite daunting now.
 "There has to be a better way!" you exclaim and sit down in front of your computer to solve the problem.