Calculate how many numbers are there between 99 and 1000 having atleast one of their digits 7?

A boy has 3 library tickets and 8 books of his interest in the library. Of these 8, he does not want to borrow Mathematics Part II, unless Mathematics Part I is also borrowed. In how many ways can he choose the three books to be borrowed?

Given that 5 flags are of different colours. Calculate how many different signals can be generated if each signal requires the use of 2 flags, one below the other?

Compute n!/ r!(n-r)!, when n=5 and r=2.

Determine the number of permutations of the letters of the word ALLAHABAD.

How many automobile license plates can be made, if each plate contains two different letters followed by three different digits?

A box contains two white, three black and four red balls. In how many ways can three balls be drawn from the box, if at least one black ball is to be included in the draw?

How many 3-digit even numbers cab be formed from the digits 1, 2, 3, 4, 5, 6 if the digits can be repeated?

How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

How many 5-digit telephone numbers can be constructed using the digits 0 to 9 if each number starts with 67 and no digit appears more than once?

. A coin is tossed 3 times and the outcomes are recorded. How many possible outcomes are there?