Which one of the following is not a prime number?

There are 154 beads in a rosary and all are coloured, either RED or BLUE or GREEN. The number of blue ones is three less…

a, b, c and d are negative integers. If a<sup>b</sup> + a<sup>c</sup> + a<sup>d</sup&gt…

To write all the page numbers of a book, exactly 136 times digit 1 has been used. Find the number of pages in the book.

The solution to the inequality 12x - 66 $$ \leqslant $$ 6 is :

The unit digit in the product of 3 × 38 × 537 × 1256 is :

$$\frac{{\left[ {\left( {888 \times 888 \times 888} \right) - \left( {222 \times 222 \times 222} \right)} \right]}}{{\le…

$$\frac{1}{{20}}$$ $$ + $$ $$\frac{1}{{30}}$$ $$ + $$ $$\frac{1}{{42}}$$ $$ + $$ $$\frac{1}{{56}}$$ $$ + $$ $$\frac{1}{{…