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.

3-Position Synthesis with Inversion Method using Unigraphics NX4 Sketch - Part 2

In previous posts, the fixed pivot points were determined from the moving pivot points. We can get result that can't be fitted in our design due to space limit. The principle of inversion can be applied to solve this problem. The first step is to find the three positions of the ground plan that correspond to the three desired coupler positions.

1) Draw desired fixed pivots (O2 and O4) and moving pivot points. Red lines are three desired positions of links (moving pivots).

2) Draw lines to make fixed relations between the ground plane (O2O4) and the second coupler position.
3) Transfer the ground position to the first coupler position using same relations developed in previous step as shown in dashed lines. Name new ground positions as O'2 and O'4 respectively.

4) Draw lines to make fixed relations between the ground plane (O2O4) and the third coupler position (A3B3).

5) Transfer the ground position to the first coupler position using same relations developed in previous step as shown in dashed lines. Name new ground positions as O''2 and O''4 respectively.

6) Draw lines O2O'2 and O'2O''2, bisect both lines and extend the perpendicular bisectors until they intersect. Label the intersection G.

6) Draw lines O4O'4 and O'4O''4, bisect both lines and extend the perpendicular bisectors until they intersect. Label the intersection H.

7) Draw O2G, GH and O4H. Now we get G and H as inverted fixed pivot points of moving link O2O4.

Let's see how it moves in [3-Position Synthesis with Inversion Method using Unigraphics NX4 Sketch - Part 3]