In how many ways can the letters of the word 'HEADER' be arranged?
In how many different ways can the letters of the word 'LEAD' be arranged in such a way that the vowels always come together?
In an examination, a candidate is required to pass all five different subjects. The number of ways he can fail is:
How many numbers can be made with digits 0, 6, 5 which are greater than 0 and less than a million?
(Note : digits can be repeated)
How many 3-digit numbers can be formed from the digits 4, 2, 5, 6, 3 and 9, which are divisible by 5 and none of the digits is repeated?
There are 5 doors to a lecture room. In how many ways can a student enter the room through a door and leave the room by a different door?
In how many different ways can the letters of the word 'MATHEMATICS' be arranged so that the vowels always come together?
In how many different ways can the letters of the word 'RETAIL' be arranged in such a way that the vowels occupy only the odd positions?
Nine chairs are numbered 1 to 9. Three women and four men wish to occupy one chair each. First the women chose the chairs from amongst the chair marked 1 to 5; and then the men select the chairs from amongst the remaining. The number of possible arrangements is
An intelligence agency forms a code of two distinct digits selected from 0, 1, 2, …., 9 such that the first digit of the code is nonzero. The code, handwritten on a slip, can however potentially create confusion, when read upsidedown-for example, the code 91 may appear as 16. How many codes are there for which no such confusion can arise?