To enter numbers choose a square by clicking on it.

Only one number per square is allowed.

Once a number is entered, the cursor will jump to the next square for your convenience. If “across” definitions are selected, the next square will be the one to the right. If “down” definitions are selected, the next square will be the one below.

You can use the arrow keys to move inside the crossword grid.

You can use the CHECK button to see if the squares have the correct number. Incorrect numbers will temporarily appear in red.

Click on the CLEAR button to delete the numbers in all the boxes automatically.

Click on the NEW CROSSWORD button for play a new crossword puzzle.

It is better to try and do mentally the arithmetic operations in the definitions. It is true that some of them may be difficult, but just by trying you will be exercising your mind.

If arithmetic operations turn up to be complicated, it is better to use paper and pencil to solve them. If you use a calculator operations will be too easy, there will be no mental exercise and solving the game will be useless.

Searching for shortcuts or tricks for calculations is also beneficial because you will be using your memory at the same time as you employ strategies and exercise logical thinking. For example, it is easier to mentally add 1533 plus 2257 if we first do 1000 + 2000 = 3000, then 500 + 200 = 700 + the previous result = 3700, after that we do 30 + 50 = 80 + the previous result = 3780 and finally we do 7 + 3 = 10 + the previous result = 3790. You can search for more tricks or calculation techniques in Google.

If numbers in an operation are too long you may be able to deduce part of the result at a guess. For the rest of the digits you can use the definitions of the numbers that cross the number in question. Let’s consider, for example, 35637 minus 11894. We will immediately realise without any calculation that the first digit of the result is going to be 2 and the last is going to be 3 (2xxx3). The other three digits will be probably deduced with the definitions of the numbers that cross the number we need to find.