With the usual arithmetic puzzles, a formula of numbers and operators is given and the result is to be calculated from this instruction. In order to challenge and promote personal thinking, these arithmetic puzzles turn the principle around: the brain teasers define the operands and the result.

Unfortunately, the operators are missing in the calculation. You don’t see at first glance how the numbers have to be combined to produce the result. Tips for solving the exercises: It is often easier to solve the tasks by working from the last operand to the left.

## Sample of Missing Operator Puzzles

Which operators (+, -, *) are missing between the numbers so that the calculations are correct? Do pay attention to dot before dash calculation, but solve the tasks from left to right.

Example 1 (Easy):

1 _ 8 _ 5 = 13

## Solution for Example 1

For the correct result you have to insert a multiply and a addition operator.

1 * 8 + 5 = 13

Example 2 (Easy):

5 _ (10 _ 6) = 65

## Solution for Example 2

If you multiply 10 and 6 you are close to the final result. Just add the 5 and your have the correct result.

5 + (10 * 6) = 65

## Some more brain puzzles with missing operators

Puzzle 3:

17 _ (8 _ 10) = 306

## Solution for Puzzle 3

17 * (8 + 10) = 306

Puzzle 4:

(20 _ 11) _ 19 = 171

## Solution for Puzzle 4

(20-11)*19 = 171

Puzzle 5:

18 _ 28 _ 24 = 22

## Solution for Puzzle 5

18 + 28 – 24 = 22

Puzzle 6:

20 _ (31 _ 48) _ 3 = 6

## Solution for Puzzle 7:

20+(31-48)+3 = 6

Puzzle 7:

8 _ (41 _ 22 _ 20) = 489

## Solution for Puzzle 8:

8+(41+22*20) = 489

Puzzle 8:

25 _ 11 _ 31 _ 47 = -269

## Solution for Puzzle 8:

25-11*31+47 = -269

Puzzle 9:

48 _ (32 _ 15) _ 8 = 102

## Solution for Puzzle 9:

48*(32-15)/8 = 102