00:01
For this question, we're asked to describe the pattern formed by the sum of the numbers along those diagonal lines.
00:08
So let's go ahead and write down the sums first.
00:10
So this first diagonal line goes through one, and it only goes through that one.
00:15
So the sum here is one.
00:18
The next diagonal line goes only through one number as well, and it's another one.
00:23
So that's the one.
00:25
The next diagonal goes through two ones, so the sum is two.
00:29
The one after that goes through two and one, so that would be three.
00:37
The one after that goes through one, three, one, which is five.
00:42
And the one after is one, four, three, which is eight.
00:48
And the one after that is one, five, six, and one.
00:53
So that's 13.
00:56
And let's do one more.
00:58
So that's one, six, ten, and four.
01:02
So that is 21.
01:05
And we can see that you might be familiar with this, you might be not.
01:09
But we can see that starting with the third term, each term is the sum of the two previous ones...