Sequences and S...

If the sum of the first n natural numbers is 1/5 times the sum of the their squares, then the value of n is

Find out next term of the series   2, 7, 28, 63, 126, ....

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 sum of $$n$$ terms of the series whose $$n^{th}$$ term is $$n(n + 1)$$ is equal to.

The sum of nn is equal to

Refer Diagram

If CAT is $$48$$,  Z is $$52$$ Then what  is TEA equal to ?

Choose the correct statement(s):

I think of a decimal number. After I have subtracted 2.9 from it, then multiplied by 3 and then added 0.15, I get 10.5. What is the decimal number?