Maths

Pascal's Triangle is an arithmetical triangle you can use for some neat things in mathematics. Here's how you construct it:
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
.
.
.

You start out with the top two rows: 1, and 1 1. Then to construct each entry in the next row, you look at the two entries above it (i.e. the one above it and to the right, and the one above it and to the left). At the beginning and the end of each row, when there's only one number above, put a 1. You might even think of this rule (for placing the 1's) as included in the first rule: for instance, to get the first 1 in any line, you add up the number above and to the left (since there is no number there, pretend it's zero) and the number above and to the right (1), and get a sum of 1.
When people talk about an entry in Pascal's Triangle, they usually give a row number and a place in that row, beginning with row zero and place zero. For instance, the number 20 appears in row 6, place 3.

That's how you construct Pascal's Triangle. Here's an interactive version where you can specify the number of rows you want to see and from which you can bring up a large version that goes through row 19.

想要更多參考資料，可到以下網址：
http://mathworld.wolfram.com/PascalsTriangle.html

Pasca: （n.）1. 壓力的單位(=1牛頓/米的次方)
2. (P-)程序設計語言之一

triangle:三角形