Sequences and S...

How many combinations of two-digit numbers having 8 can be made from the following numbers?
8, 5, 2, 1, 7, 6

The positions of the first and the fifth digits in the number 83256479 are interchanged. Similarly the positions of the second and the sixth digits are interchanged and so on. Which of the following will be the third to the right of the seventh digit from the right end after rearrangement?

The spread sheet on the right contains 20 cells. A cell In a spread sheet can be identified fIrst by the column letter and then by the row number. For example,. the number 10 is found in cell C4. If the number in cell A3 =B4-3(E2 +D4) then which of the following must be the number in cell E2?

In numbers from $$1 \ to\  100$$ the digit "$$0$$" appears ____________times.

The greatest number that can be formed by the digits $$7,0,9,8,6,3$$

The area of a triangle whose vertices are $$(a, c+a), (a, c) $$ and $$(-a, c-a) $$ are 

In the series given below. count the number of 9s, each of which Is not immediately preceded by 5 but is immediately followed by either 2 or 3. How many such 9s are there?
1 9 2 6 5 9 3 8 3 9 3 2 5 9 2 9 3 4 8 2 6 9 8

How many numbers amongst the numbers 9 to 54 are there which are exactly divisible by 9 but not by 3?

Refer Diagram