How many 9's are sandwiched between 6 and 7 in 696996676979669779667?

Find the missing number in the given series 6, 14, 36, 98, ?

Find the missing number in the given series 2, 65, 7, 59, 12, 53, ?, ?

Find the missing number in the given series 7, 26, 63, 124, 215, 342, ?

Find the next number in the series: 9, 20, 38, 65, ___

Find the missing number in the given series 7, 18, 40…….?....117, 172