How many odd numbers of six significant digits can be formed with the digits 0, 1, 2, 5, 6, 7 when no digit is repeated?

The number of ways four boys can be seated around a round table in four chairs of different colours is

A polygon has 44 diagonals. The number of the sides is

The number of permutations by taking all letters and keeping the vowels of the word COMBINE in the odd places is