### 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.

### SANDEX Indexing Box

In my design, I've been using several indexing boxes from the Japanese company "Sankyo Seisakusho". The model of the indexing box is "SANDEX". It is a generic name for our cam units that combine a simple and ideal indexing mechanism, the "Roller gear cam mechanism". Sankyo's original cam technology, consisting of a roller gear cam and a follower spider (turret) is used to complete the units. SANDEX indexing units have always enjoyed high sales and are responding to industrial needs where the new technologies are evolving.

The indexing units must accommodate three types of basic motion -- that is the indexing drives with an intermittent rotating motion, the oscillating drives with their oscillating rotating motion, and the roller drives with a continuous rotating motion. SANDEX units have a higher number of indexes, index angle, and degree of design freedom than other indexing mechanisms. They are more rigid and have higher output values relative to the size of the unit, and they can eliminate backslash completely, performing at high-speed. A broad lineup of models and sizes will meet the needs of automated rotary machines of all sizes and specifications from the world smallest miniature indexes to the largest class of super-size indexes.

In addition, one model with parallel input/output shafts is also available, using a parallel mechanism as an "ideal flat cam". This is optimum for Conveyer drives with a large feed pitch or indexing drives with relatively long stopping interval.

This is the example of indexing movement (intermittent rotation).

More details about how to select the indexing drive and calculation example, please visit Ezy Mechanic.

Source: http://www.sankyo-seisakusho.co.jp/english/2index.htm