**Puzzle 1:** Which number replaces the question mark?**Answer:** 45

Consider diagonally

15 + 15 = 30 35 + 5 = 40

**30 + 15 = 45 40 + 5 = 45**

60 + 15 = 75 50 + 5 = 55

**Puzzle 2:** Which number replaces the question mark?

3, 5, 13, 43, 177, ?, 5353

**Answer:** 891

3 x 1+ 2 = 5

5 x 2 + 3 = 13

13 x 3 + 4 = 43

43 x 4 + 5 = 177

**177 x 5 + 6 = 891**

891 x 6 + 7 = 5353

**Puzzle 3:** Which number replaces the question mark?**Answer:** 7

Sum of the numbers in each part is 25.

8 + 5 + 5 + ? = 25

? = 25 – 18

**? = 7**

**Puzzle 4:** Which number replaces the question mark?

If 2 + 3 = 8

3 + 7 = 27

4 + 5 = 32

5 + 8 = 60

6 + 7 = 72

Then 7 + 8 =?

**Answer:** 98

This equations follow the following logic;

2 + 3 = (2 x 3) + (2 x 1) = 6 + 2 = 8;

3 + 7 = (3 x 7) + (3 x 2) = 21 + 6 = 27;

4 + 5 = (4 x 5) + (4 x 3) = 20 + 12 = 32;

5 + 8 = (5 x 8) + (5 x 4) = 40 + 20 = 60;

6 + 7 = (6 x 7) + (6 x 5) = 42 + 30 = 72;

So to find the missing number;

**7 + 8 = (7 x 8) + (7 x 6) = 56 + 42 = 98****.**