Quicker Maths

name of the exchange. How many such arrangements of 3 letters is it possible to devise from the 26 letters of the alphabet?

I am sure you know that Bangalore is over a thousand miles away from Calcutta, and also that sound travels at 1100 feet per second.
Do you think there was any difference in the times at which the music was heard by Vasantha and myself? If so which one of us did hear the given note first?

and what is even more interesting is the sum of the proper divisors of 284 equals 220.
So far about 100 pairs of amicable numbers are known. Can you find some in four digits?

by subtracting two times the number of wrong answer from the number of correct answers.
Can you tell how many problems she solved correctly?

It takes seven second for this clock to strike seven gongs. Now how long do you think it will take for striking ten gongs.

they had forgotten to write their names.
Parveen returned the papers to students at random.
What is probability that none of three students will get the right paper?

Compute how many inches should be added to either the radius or height to give the same increase in volume?

I’ve got denominations of 1 Paise, 5 Paise, 10 Paise, 25 Paise, 50 Paise, Re 1/-, Rs2/-, Rs5/-, Rs10/-, Rs20/-, Rs50/-, Rs100/-, Rs500/- and Rs 1000/-.
How many different amounts of money can I make by taking one or more of each denomination?
What do you think my answer was?

as rollers.
When the rollers have made one revolution, how far will the safe have moved forward?

which is one-half of the height of the last bounce.
How far approximately will the ball have travelled when it comes to rest?