Puzzles - Number puzzles

88.
Answer
:
2
Explanation
:
The sum of the numbers along each side of the triangle is always 15.

89.
Answer
:
16
Explanation
:
As you move downwards, numbers increase by 3, then 2, then 1, before repeating this pattern.

90.
Answer
:
7
Explanation
:
The numbers in each row of the diagram add up to 18.