81.
The 9th term of an A.P. is 449 and 449th term is 9. The term which is equal to zero is

82.
If Sn denote the sum of n terms of an A.P. with first term a and common difference d such that $$\frac{{{S_x}}}{{{S_{kx}}}}$$ is independent of x, then

83.
The sum of n terms of two A.P.’s are in the ratio 5n + 4 : 9n + 6. Then, the ratio of their 18th term is

84.
The sum of first 20 odd natural numbers is

85.
The next term of the A.P., $$\sqrt 7 ,$$ $$\sqrt {28} ,$$ $$\sqrt {63} ,$$ . . . . . .

86.
How many 2-digit positive integers are divisible by 4 or 9?

87.
What is the sum of all 3 digit numbers that leave a remainder of '2' when divided by 3?

88.
Given A = 265 and B = (264 + 263 + 262 + ..... +20), which of the following is true?

89.
The sum of the three numbers in A.P is 21 and the product of the first and third number of the sequence is 45. What are the three numbers?

90.
If a rubber ball consistently bounces back $$\frac{{2}}{{3}}$$ of the height from which it is dropped, what fraction of its original height will the ball bounce after being dropped and bounced four times without being stopped?