It is a strange sequence. Each number describes the resemblance of the previous one, except the first one.

11 describes the previous '1' which contains one '1'

21 describes the previous '11' which contains two '1'

1211 describes the previous '21' which contains one '2' and one '1'

111221 describes the previous '1211' which contains one '1', one '2' and two '1'.

So the next sequence will be 312211, that is the previous '111221' contains three '1', two '2' and one '1'.

A) 1009 | B) 991 |

C) 2000 | D) 1000 |

Explanation:

Given total number of rats = 999919

999919 = 1000000 - 81 = = (1000+9)(1000-9) = 1009 x 991.

Since there were more rats than there were cats, 991 cats killed 1009 rats each.

A) 8 | B) 24 |

C) 16 | D) 4 |

Explanation:

There are 16 small cubes attached to the outer walls of the cuboid.

Therefore remaining inner small cubes will be the cubes having two sides green coloured.

So the required number = 24 - 16 = 8

1113122110

In given series 2nd number gives number of which digits present in the 1st number and so on continues for 3rd ,4th,...

Here 1st no. has only one zero, so 2nd no. is 10 and 2nd no. has one 1 and one 0,so 3rd no. is 1110, so like that 5th no. has one 1,one 3,one 2,two 1's and one 0.So the next no. is 1113122110.