This is the most popular circular calculation scale, which is not added, subtracted... It is a basic calculation scale that can easily calculate multiplication, division, square, and triple, and is used in all fields. Calculation type: General exclusion, proportional (exponent hundred ratio), square and cu. Reverse side: Length and area, volume, mass, temperature, pressure, speed, etc. are listed for unit conversion Scale: D, C, CI, A, K (surface) Dedicated storage case, instruction manual included.