In a certain code language, '+' represents '÷', ' - '

In each of the following series, one term is missing. Find the missing term.

2, 6, 15, 31, 56, ?

226, 171, 124, 85, 54, ?

What should come in place of (?) question mark in the given number series.

2, 6, 15, 31, 56, ?

What will come in place of (?) Question mark in the given number series.

500, 489, 467, 434, 390, 335, ?

What will come in place of the question mark (?) in the following series?

10, 410, ?, 710, 760, 785

What should come in place of (?) question mark in the given number series.

2, 6, 12, 20, ?, 42

116, 118, 124, 136, 156, ?

8, ?, 29, 57, 113, 225

Find the missing term in the series:

1, 4, 9, 16, 25, ?, 49

76, 80, 89, 105, ?, 166