Enter your number:

Enter four numbers, separated by any characters, spaces, or symbols. Go, start the game, the timer is on. The number needs to be between 1 and 13.
e.g.
Following are ok:
2 3 4 5
2 3 4 5
2*3*4*5
2a3b4c5
2--3 4 5

Following are not:
2 3 45
2 3 6 27

Random number:

Random 4 numbers, between 1 and 13, will be given, start the game, the timer is on.

Enter expression:

Enter your answer (arithmetic expression) here, then press 'Start' to confirm. This is one way to input an expression.
Using the expression bar below is another way, which is simpler.

Timer:

The timer counts in seconds, starting from when the game begins.

Solved:

Resolved/total solutions
For eaxample: 1/3
Resolved: 1
Total: 3
2 left

Message:

Message here.

Expression bar:

↑ [*|] c x Left-up ↑: Send expression from expression bar to Edit input. Right-up [*|]: switch grid/operation display. Left-down x: Cancel current or back to main page. Right-down c: Clean operation in expression bar.

+-*/

+ - * /

Parentheses ()

Parentheses ()

Number

drag number, swap position Number

Solutions

For 5 6 7 8, there are 3 solutions:

1. Solved by ask. 5 seconds from last solution.
2. Not solved, press ******** to ask for.
3. Solved. take time 18 seconds from last solution.