Puzzles - Number puzzles

82.
Answer
:
1
Explanation
:
Taking any series of 3 numbers in a straight line in the diagram, their total is always 19.

83.
Answer
:
1
Explanation
:
Working from the top row, add the values in adjacent boxes and put this sum in the box directly below, working towards the centre. Repeat this pattern starting at the bottom row as well.

84.
Answer
:
4
Explanation
:
Working in rows, from top to bottom, the sum of the digits in each row increases by 2 each time, from 8 to 16.