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.

Four-bar linkage Synthesis using Unigraphics NX4 Sketch

In most design problems, we need to design the mechanism that moves between required positions. In this post, we will show the motion generation synthesis method to control a line in the plane to move in sequential positions. Any CAD software can be used to do this. But here we use Unigraphics NX4 sketch to draw and use "Animate Dimension" command to simulate the movement of all concerned links.


Assume that we need to design the mechanism to move line AB to A'B'. A simple and most commonly used four-bar linkage will be used here. Let's see how to find the fixed pivoting point at the ground.

1) Draw the link AB and A'B' in its desired positions in sketch of Unigraphics NX4 sketch (or any other CAD software) as shown in the above figure.

2) Draw construction lines from point A to A' and bisect line AA' and extend the perpendicular bisectors in convenience direction. (The choice is yours).

3) Select any convenient point on bisector as the fixed pivot O2. For this example, we use length O2A = 500 mm.
4) Draw line O2A as link 1.
5) Do the same for point B and B'. Draw construction lines from point B to B' and bisect line BB' and extend the perpendicular bisectors in convenient direction.

6) Select any convenient point on bisector as the fixed pivot O4. For this example, we select 60o angle between O4B and O4B'
7) Draw line O4B as link 2.
8) Draw line O2M and set the same length as O2A.
9) Draw line O4N and set the same length as O4B.
10) Draw line MN and set the same length as AB.
11) Set angular dimension between O4B and O4N to any desired value e.g. 45 degrees.

12) Select "Animate Dimension" Command in Unigraphics NX4 sketch and set lower limt to 0 and Upper limit to 60 and Steps/Cycle to 150 (the more steps, the smoother simulation).


See the results of four-bar linkage synthesis in the following video clip.



Further reading:

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