What's the missing number here in this Pie ?

Missing no. is 6

Because all sectors having 10+11 = 21 4+17 = 21 8+13 = 21 15+ ? = 21 , so 6

The missing number is 6.The two numbers opposite each other always total 21 : 15 + 6 = 21.

By deducing the logic used in the table below, can you find the missing number?

Find the value of the missing number in the table below.