Improve math skills of your kids - Learn step-by-step arithmetic from Math games

Math: Unknown - Step-by-step math calculation game for iOS.


Math: Unknown is much more than a math game. It is a step-by-step math calculation game which will teach users how to calculate in the correct order rather than just asking only the final calculated results.

The app consists of four basic arithmetic operations which are addition, subtraction, multiplication and division. In order to get started, users who are new to arithmetic can learn from animated calculation guides showing step-by-step procedures of solving each type of operation. It is also helpful for experienced users as a quick reference.

Generally, addition and subtraction may be difficult for users who just start learning math especially when questions require carrying or borrowing (also called regrouping). The app helps users to visualize the process of carrying and borrowing in the way it will be done on paper. Once users understand how these operations work, they are ready to learn multiplication and division.

For most students, division is considered as the most difficult arithmetic operation to solve. It is a common area of struggle since it requires prior knowledge of both multiplication and subtraction. To help users understand division, the app uses long division to teach all calculation procedures. Relevant multiplication table will be shown beside the question. Users will have to pick a number from the table which go into the dividend. Multiplication of selected number and divisor is automatically calculated, but the users have to do subtraction and drop down the next digit themselves. Learning whole calculation processes will make them master it in no time.

Math: Unknown is a helpful app for students who seriously want to improve arithmetic calculation skills.

How to use Unigraphics NX4 Motion Simulation in Timing Diagram Design Process - Part 3

In [How to use Unigraphics NX4 Motion Simulation in Timing Diagram Design Process - Part 2], we've finished setting the driver of revolute joint of the indexing mill. Then let's set the joint for the punch die.

Movement of the punch die is different from the indexing mill. It moves only in linear motion along Z axis (normal to top face of indexing mill). The joint for this kind of movement is called "Slider" joint. Here is how to set it:

1. Select Joint command.
2. Select "Slider" joint icon in the joint dialog box.
3. Select first link icon.
4. Select link "Die" as we previously created


5. Click at the "Orientation on the first link" icon.
6. Select "Point" from the drop-down menu.
7. Select center point of the cylinder as shown above to define the location of the slider joint.


8. Select "Vector" from the drop-down menu to define the direction of the slider joint.
9. Select the bottom face of cylinder to define the vector perpendicular to that plane. See the Z axis pointing downward.
10. Rename the slider joint to "J_Die".
11. Click Ok to confirm.

The slider joint setting procedures are almost done. Still to set the driver of this joint.


1. Right-click at the slider joint J_Die and select Edit to open the dialog box.
2. Change the slider joint motion driver to "Constant".
3. Type any value in the velocity text box e.g. 50. This sets the velocity of this slider joint to 50 mm/s.
4. Click Ok to confirm.

We've finished the setting procedures for motion simulation and we can now start simulation. But please note that the movement of indexing mill and punch are still not the same as what we need.


To see the motion simulation, follows the steps below:

1. Select "Animation" command
2. Enter the time for simulation in seconds e.g. 1.8 seconds mean the cycle time of machine speed of 2,000 pcs/h.
3. Enter number steps for simulation. The more steps, the smoother simulation results. Here I put 360 steps, which is easy to trace for every 1 degree in timing diagram.
4. Click Ok to confirm.


5. Change the domain to steps instead of time, just for easier tracing purpose.
6. Click "Play" button to see the simulation.


We can find the interference between the indexing mill and punch die during the motion simulation using UG NX4 motion simulation module. This is because the functions set for both drivers are not as per the timing diagram designed previously.

Next post will show how to use "graphing" and "spreadsheet run" to set the UG NX4 motion simulation as per the timing diagram. And you can watch for the result of effort to optimize the timing diagram in 3D Motion.

Further reading:

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