Number Series Questions

In the following question, select the missing number from the given series.
1, 3, 6, 10, 15, ?

In the following question, select the missing number from the given series.146, 137, 128, ?, 110, 101

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series. 4, 13, 40, 121, ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

17, 27, 42, 62,?

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

1/4, 0.65, ?, 29/20, 1.85

Find the next number in the given series. 9, 11, 15, 17, 21, 23, ?

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.
400, -200, 100, ? , 25, -12.5

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

11, 121, 1331, 14641, ?