Look at this series: 2, 4, 6, 8, 10, ... What number should come next?

Choose the correct alternatives that will continue the same pattern and replace the question mark (?), in the following number series.
99, 33, 36, 12, 15, 5, ?

Which of the following numbers will replace the question mark (?) in the given series?
2548, 3150, ?, 4624, 5508​

What should come in place of the question mark (?) in the following series?
2, 6, 12, 20, ?

What should come in place of the question mark (?) in the given series?
91, 102, 119, 142, 171, ?

What should come in place of the question mark (?) in the given series?
108, 122, 139, 159, 182, 208, ?

Select the number from among the given options that can replace the question mark (?) in the following series.
44, 55, 68, 83, 100, ?