1. The famous mathematician associated with finding the sum of the first 100 natural numbers is

2. If the first term of an AP is – 5 and the common difference is 2, then the sum of the first 6 terms is

3. What is the common difference of an AP in which a18 – a14 = 32?

4. For the AP -3, – 7, – 11,… can we find directly a30 – a20 without actually finding a30 and a20?

5. The list of numbers – 10, – 6, – 2, 2,… is

6. If 7 times the 7th term of an AP is equal to 11 times its 11th term, then its 18th term will be

7. The 4th term from the end of an AP – 11, -8, -5,…, 49 is

8. In an AP, if a = 3.5, d = 0 and n = 101, then an will be

9. The sum of first 16 terms of the AP 10, 6, 2, … is

10. In an AP, if a = 1, an = 20 and Sn = 399, then n is equal to

11. The first four terms of an AP whose first term is – 2 and the common difference is-2 are

12. In an AP, if d = – 4, n = 7 and an = 4, then a is equal to

13. The 11th term of an AP -5, -5/2, 0, 5/2 ……………

14. If the common difference of an AP is 5, then what is a18 – a13?

15. If the 2nd term of an AP is 13 and 5th term is 25, what is its 7th term?

16. Two APs have the same common difference. The first term of one of these is – 1 and that of the other is – 8. The difference between their 4th terms is

17. Which term of an AP : 21, 42, 63, 84,… is 210?

18. Justify whether it is true to say that -1, , -2, … forms an AP as a2 – a1 = a3 -a2

19. The 21st term of an AP whose first two terms are – 3 and 4, is

20. The sum of first five multiples of 3 is