Binomial Expansion

Problem : What is the 5^th entry in Row 12 of Pascal's Triangle?

Problem : What is the 3^rd entry in Row 10 of Pascal's Triangle?

Problem : What is the 7^th entry in Row 9 of Pascal's Triangle?

Problem : What is the 15^th entry in Row 15 of Pascal's Triangle?

Problem : If the r ^th entry in Row 6 of Pascal's Triangle is 15, what are the possible values of r ?