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.

Sankyo AD Alpha Series - Dial Index

If you are looking for a strong indexing box for your dial application, you can have a look at Sankyo AD Alpha Series.

Apart from its product specifications, you'll find useful technical information regarding indexing drives.

Sankyo's AD/Alpha Series
features a low profile design cast iron housing with a ground pilot flange for mounting dial plates, hub less gears, or weldment fixtures. Above the indexing dial, a second dial mounting surface is stationary and hollow to allow air lines, wiring or bearings for a shaft to be routed through the tolerance bore. A globoidal cam rotates Sankyo made needle bearing type cam followers. Optimizing the cam follower diameter inherently maximizes torque transfer and extends the life hours due to fewer rotations with increased surface contact.

Multiple index periods offer continuous or on demand duty cycles with the indexing flange locking in position within 30 arc seconds during the dwell period. The output flange turret is mounted with top and bottom tapered bearings which supports large bending moments, maintain rigidity and reliability. These versatile units index in both directions, oscillate or perform non-patterned motions with a continuous lead cam using servo driven motors. Most units are driven with geared motors that are within the height of the index unit housing. There’s no need for spacers or burning a hole in the mounting plate to accommodate for drive height interference. An optional torque limiter safety clutch mounts between the index and indexing dial plate. Torque thresholds are easily adjusted without any disassembly and a proximity sensor detects overloads.

Timing cam packages are available with inexpensive photo beam sensors or proximity switches for wash down (IP67/NEMA-6/6P) applications. The AR/Alpha ServoDEX Series shares the same housing as the AD/Alpha series but uses a constant lead cam for programmable indexing stops with a servo motor drive. Non-patterned motions, oscillating, variable or continuous speeds can be programmed to suit your current application needs or reprogrammed for the future. Repetitive accuracy is within 30 arc seconds or 0.0014” per inch of radius.

  • 2 to 32 incremental output stops, 1-dwell cam equals; 1-output stop to 1-input shaft revolution, 2-dwells for 16 to 32 stops
  • Dial diameters range from 280mm to 3600mm (1 to 12 feet) with second stationary dial mounting
  • 120° to 330° index periods with Sankyo modified sine or constant velocity (~50% CV) cam curves
  • Maximum 200 cycles per minute, bi-directional indexing, oscillating motions (non-pattern for servo driven AR/ServoDEX)
  • ±30 arcsec indexing accuracy (average ±9 arcsec), 30 arcsec repetitive, ±60 arcsec for 2-dwell cams for 16 to 32 stops
  • Painted cast iron housings are available in 8 standard sizes ranging from 70 to 450mm input to output shaft centers
  • Standard stationary hollow flange output with tolerance bore, available with optional torque limiting clutch
  • Index mounts in any position with right angle gearmotor mounting in 90° increments on either side of the index
  • Standard brushless dual voltage (230/460) gearmotors are UL & CE certified, brake motor or wash down optional
  • Variable frequency drive controller utilizes electronic braking and variable speed for gearmotors in 115-1ph, 230-1/3ph, 460-3ph volts, 50/60 Hz, UL & CE certified
  • Stop/start frequency up to 60~90 per minute (output load/reducer dependant), clutch brake or servo drives are available
  • Standard IP50 photo eye timing cam sensor package supplies dial “in position” signal to stop the motor, IP67 proximity type optional
  • Output torque limiting clutch option features quick-adjust torque setting, automatic reset every 360° & overload detect prox.
Stationary Output Flange Riser Option

This option is used if part handlers or measurement equipment are required to be mounted above the rotary indexing dial. The riser is flanged on both ends and offered in multiple lengths with a slightly smaller hollow bore than the index bore. Each riser incorporates a tolerance male centering pilot on the index output flange and for the dial plate or fixture mounting flange. The
riser is mounted to the index output flange with (4) bolts and also includes the grease fitting to be extended for easy access. Standard units are painted steel to match the beige index color but custom materials and coatings are available.

Index is shown with a riser for mounting a second fixed dial above the indexing dial. Each riser is hollow to mate to the index hollow output flange. A center pilot flange makes dial mounting concentric and precise. Dowel holes are an option.

Find more details about Sankyo AD Alpha Series - Dial Index at


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