9017.20.40.00 - Disc calculators, slide rules and other mathematical calculating instruments

HTS code 9017.20.40.00 specifically classifies disc calculators and slide rules, along with other mathematical calculating instruments not covered by more specific headings. This category encompasses devices primarily designed for performing mathematical computations, particularly those that rely on mechanical or analog principles rather than purely electronic digital processing. Examples include circular slide rules for multiplication, division, and other complex calculations, as well as various forms of analog calculators that utilize movable scales or components to arrive at a result.

This classification distinguishes itself from its sibling categories by its focus on analog mathematical calculation. HTS code 9017.20.70.00 covers plotters, which are machines for drawing graphs and diagrams, a distinct function from calculation. The "Other" category (9017.20.80) is a residual category for drawing, marking-out, and mathematical calculating instruments not otherwise specified. Therefore, items classified under 9017.20.40.00 must primarily serve a calculating function and not be plotters or fall under other explicitly defined categories.

As this is a leaf node in the HTS structure, there are no further subcategories under 9017.20.40.00. Classification at this level relies on identifying instruments whose primary purpose is mathematical calculation and which fit the description of disc calculators, slide rules, or analogous mechanical calculating devices. The absence of specific exclusions within this sub-heading means that a broad range of analog mathematical calculating instruments can be classified here, provided they are not better classified elsewhere.