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.

Engineering Plastic PEEK Polyetheretherketone

PEEK is an abbreviation for polyetheretherketone, a high performance engineering thermoplastic. It is another engineering plastic which is widely used in machine components since it has very good mechanical strength and dimensional stability, excellent thermal and chemical resistance properties and outstanding resistance to abrasion and dynamic fatigue. Its yield strength is about 92 MPa. Its density is about 1.32 g/cm3 which is 1/6 of steel.

It is a strong and stiff thermoplastic material that is often used in applications where performance at high temperatures is required. PEEK has outstanding chemical resistance as well as resistance to hot water and steam. PEEK is insoluble in all common solvents and is extremely resistant to attack by a very wide range of organic and inorganic chemicals. PEEK can be used continuously to 250°C (for short term, it can operate at 300°C) and in hot water or steam without permanent loss in physical properties. It also has high abrasion and cut through resistance combined with low coefficient of friction. So it is used a lot in sliding applications such as bearing, guide, etc. Unlike Polyamide or Nylon, PEEK has excellent hydrolysis resistance. It has very low moisture absorption.

Applications: Gears, wear strips, bushes, metering pumps, pump housings, light mountings, friction bearings, ball valve seals, wafer supports, plug parts.

PEEK is naturally tan in color and can be pigmented with a wide range of colors, allowing for easy part identification.

  • Excellent chemical resistance
  • Very low moisture absorption
  • Inherently good wear and abrasion resistance
  • Unaffected by continuous exposure to hot water or steam. Very good hydrolysis resistant, even against super heated steam
  • Very good dimensional stability
  • High thermal mechanical bearing strength
  • Creep resistant
  • Low smoke and toxic gas emissions.
  • Excellent resistance against high energy radiation. Absorbing more than 1000 M rads of irradiation with no significant reduction in mechanical properties


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