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.

Renold Roll-Ring: Self Adjusting Chain Tensioner

Roll-Ring® is a simple yet innovative chain tensioner made from a specially formulated polymer. The unique design is based upon a simple toothed ring that can be fitted to horizontal, vertical or diagonal drives in a matter of seconds, simply by placing it in-between the two strands of chain. When the drive is in use, the Roll-Ring® deforms to an elliptical shape, due to compression between the strands and completely asborbs any slack in the system. Roll-Ring® performs the job of a tensioner and a damper in one, and is ideally suited to applications where maintenance is difficult or impossible.
Vibrations in an untensioned chain drive

The Roll-Ring® chain tensioner tensions and dampens

The Roll-Ring® chain tensioner provides cost effective, time saving installation and maintenance.
The advantages over other types of chain tensioners are:
  • Free standing - no sprockets, bolts, plates, drilling or costly installation required.
  • The Roll-Ring® is easily installed where space limitations prohibit the use of conventional chain tensioners.
  • The Roll-Ring® is fitted in a matter of seconds.
  • It is ready for use without any tools, tensioning equipment or any further alignment or adjustment.
  • It is fully effective in vertical and diagonal drives.
  • The Roll-Ring® works automatically, is maintenance free and self lubricating.
  • It can be used in dusty and dirty environments.
  • The Roll-Ring® is a tensioner and damper in one, thus reducing noise levels.
  • Roll-Ring® also works in reverse mode. Roll-Ring® chain tensioners reduce chain wear and improve the quality and efficiency of the complete chain drive.
The innovative Tensioner
The Roll-Ring® chain tensioner is an elementary mechanism based on new principles and represents a major advance in technology:
  • Roll-Ring® requires minimal technical effort.
  • Its operation is astonishingly simple.
  • All functions are integrated into a single component.
  • Roll-Ring® utilises the hollow space of the associated chain drive system giving greater flexibility to designers and specifiers.
  • Automatic positioning and self lubricating.

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