What is the theme of World Tourism Day

80, ?, 240, 80, 20, 4 

251, 130, 274, ?, 301, 76 

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

45, 68, 114, 183, 275, ?

What value should come in the place of (?) in the following number series?

500, 789, 428, ?, 340, 965

Which of the following numbers will replace the question mark (?) in the given series?

17, 30, 44, 59, 75, ?

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

52, 61, 79, 106, 142, ? 

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

7, 14, 28, 56, 112, ?

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

15, 26, 39, 56, ?, 98

Find the missing number, in the given number series.

42, 52, 72, 112, 192, ?