The basics

One of the numbers on the grid is trying to hide from you!

Arithmo - Hidden One follows the basic Arithmo rules. You are given two items in the beginning: a grid which is filled with numbers, and an Equa-X number. All of the numbers on the grid can be connected together in threes to equal the Equa-X except for one hiding number that doesn’t want to be caught!

Remember that in the Arithmo world, "connected" always means any 3 adjacent numbers on the grid that you can connect together in a straight vertical, horizontal, or "L" shaped line, and add, subtract, multiply, or divide together to make some product.

There’s one problem in each puzzle: somewhere on the grid, a number is hiding from you! Your goal is to figure out which number on the grid cannot be used in any combination of 3 adjacent connected numbers to make Equa-X. Let’s explain this in a little more detail, and you’ll get the hang of it in no time at all!

Rules of the Game

You are given a grid ranging in size from 2x3 to 6x6 and also an Equa-X number between 13 and 24. For example, let’s say you are given Equa-15. On your grid, almost all of the numbers can be connected together in threes, and using addition, subtraction, multiplication, or division, can be made to equal 15 if connected to the right numbers. (Again, "connected" means that you can connect 3 adjacent numbers together in a straight vertical, horizontal, or "L" shaped line on the grid.)

However, there is one, and only one number on the grid that CANNOT be used with ANY of the other numbers to equal 15, no matter what math you use. Your goal in each puzzle is to eliminate all other possibilities and find out which number will not work with any others! That number is your solution.

The easiest way to find the solution is to start making connections on your own. If you can connect any three numbers together in a horizontal, vertical, or "L" shaped line and cause them to equal 15 when added, subtracted, multiplied, or divided together in any order or combination, then you know those three numbers are not your answer. Instead, these numbers are clues which will help you solve the mystery!


12 8 7 11 5 2
4 9 11 5 6 8
10 2 7 10 6 4
1 3 8 11 9 8
7 2 7 10 5 4
5 1 7 9 6 10

In this 6x6 grid, our task is to find the number which can not create Equa-14, no matter what we try. In other words, when you connect that number with two numbers in a straight or "L" shaped line, the three numbers should not be able to equal 14 no matter what kind of math you do.

The only way for you to find the solution is to start matching up triplets and doing the math. After some time you’ll realize that one number on the grid stubbornly refuses to match with any other adjacent numbers to equal 14 and, in this example, that is number 6 in 2nd row, 5th column.

Skill levels

Arithmo – Hide and Seek tasks are divided into 7 levels: Novice, Easy, Medium, Difficult, Advanced, Killer, Genius

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