How many terms of the series 1 + 5 + 9 + ....must be taken so that their sum is 190?

The 13^th term of an A.P is 3 and the sum of the first 13 terms is 234.Find the common difference and the sum of first 21 terms.

Find the sum of all natural numbers between 300 and 600 which are divisible by 7.

Which of the following list of numbers form an AP? If they form an AP, write the next two terms:
4,10,16, 22, ...

Which of the following list of numbers form an AP? If they form an AP, write the next two terms:
1,-1,-3, -5, ...

Which of the following list of numbers form an AP? If they form an AP, write the next two terms:
-2, 2, -2, 2, -2

Which of the following list of numbers form an AP ? If they form an AP, write the next two terms:
1, 1, 1, 2, 2, 2, 3, 3,  3

Determine the AP whose 3rd term is 5 and the 7^th term is 9.

In a flower bed, there are 23 rose plants in the first row, 21 in the second, 19 is the third, and so on. There are 5 rose plants in the last row. How many rows are there in the flower bed?

If the sum of the first 14 terms of an AP is 1050 and its first term is 10, find the 20th term.