The total number of 3-digit numbers, whose sum of digits is 10, is ______.

The number of function f from {1, 2, 3, ...,20} onto {1, 2, 3, ..., 20} such that f(k) is a multiple of 3, whenever...

The number of 4 letter words (with or without meaning) that can be formed from the eleven letters of the word ‘EXAMINATION’ is_______.

Some identical balls are arranged in rows to form an equilateral triangle. The first row consists of one ball, the second row consists of two...

The number of 4-digit numbers which are neither multiple of 7 nor multiple of 3 is ______.

The number of six letter words (with or without meaning), formed using all the letters of the word 'VOWELS', so that all the consonants never...

Total number of 6-digit numbers in which only and all the five digits 1, 3, 5, 7 and 9 appear, is

The number of three-digit even numbers, formed by the digits 0, 1, 3, 4, 6, 7 if the repetition of digits is not allowed, is...

If ${ }^1 \mathrm{P}_1+2 \cdot{ }^2 \mathrm{P}_2+3 \cdot{ }^3 \mathrm{P}_3+\ldots+15 \cdot{ }^{15} \mathrm{P}_{15}={ }^9 \mathrm{P}_{\mathrm{r}}-\mathrm{s}, 0 \leq \mathrm{s} \leq 1$, then ${ }^{\mathrm{q}+\mathrm{s}} \mathrm{C}_{\mathrm{r}-\mathrm{s}}$ is...

A number is called a palindrome if it reads the same backward as well as forward. For example 285582 is a six digit palindrome. The...