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37. A blue book, a green book and a purple book are stacked on top of each other.
The bottom blue book has 220 pages, the middle green book has 200 pages, and the top purple book 210 pages.
How many pages lie between the first page of the purple book and the last page of the blue book?
The purple book faces in a different direction to the other two books.
The purple book's first page is at the bottom of the book.
D. There are 420 pages between the first page of the purple book and the last page of the blue book.
What is the missing number?
This is an example of a look and say sequence.
Work out second line:
First line is: 3
i.e first line has one (3).
Therefore, 1 3
Work out third line:
Second line is: 1 3
i.e second line has one (1), and one (3).
Therefore, 1 1 1 3
Reading from the second line from the bottom:
There is one (3), two (1), one (3), two (1), three (2), two (1), and one (3).
Therefore: 1 3 2 1 1 3 2 1 3 2 2 1 1 3