Book Maths Puzzle Numerical Ability

23*53 = 8
17*39 = 11
49*24 = 13
66*32 = ?

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Book Other Question

A Train 150 meters long passes a mile store in 15 sec and another train of same length travelling in opposite direction in 8 sec. what is thw speed of the second train? what's the next number in the series?

4,6,12,18,30,42,60,72,102,108, ??