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 PA Polyamide

PA is the abbreviation of Polyamide. The commercial name of polyamide is Nylon. Nylon is an engineering thermoplastic which is commonly used in textiles, automotive, carpet and sportswear due to its extreme durability and strength. It has tensile strength about 80 MPa which is higher than POM. Solid nylon is used for mechanical parts such as machine screws, gears, cams, bearings, guides, rollers, and other low- to medium-stress components previously cast in metal. Nylon is frequently used as a replacement for bronze, brass, aluminium, steel and other metals, as well as other plastics, wood, and rubber.

Engineering-grade nylon is processed by extrusion, casting, and injection molding. Nylon price is approximately 2 times of the price of POM (Polyacetal). Working temperature when using Nylon should be within - 50oC to 160oC. Nylons are available in various colors such as white, blue, black, etc. One important property of Nylon that should be noted when use it to make machine components is moisture absorption. Moisture has significant effect on properties of Nylon. It may change in size which may cause problems.

Notable material features:
  • Very good physical properties. High tensile strength and modulus of elasticity
  • High impact resistance, a high heat distortion temperature. Very good heat resistance.
  • Excellent wear resistance. Resists wear, abrasion, and vibration
  • Excellent chemical resistance. Can withstand contact with chemicals, alkalies, dilute acids or oxidizing agents.
  • Nylon is NOT moisture Resistant. Moisture has significant effect on properties.
  • Moderate to high price
  • Fair to easy processing
Applications:
  • Electrical connectors
  • Gear, slide, cams and bearings
  • Cable ties and film packaging
  • Fluid reservoirs
  • Automotive oil pans

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