Particle size "originally referred to the thickness of particles in the exposed area of the film, and extended to the military field. In combat calculations," particle size "is usually used to describe the accuracy of combat calculations. The coarser the granularity, the rougher and more macroscopic the calculation; The finer the granularity, the more precise and specific the calculation. Combat computing is an important means of assisting decision-making, and its "granularity" is related to the effectiveness of computing and the scientific nature of command decision-making. Due to different calculation purposes or limitations in calculation conditions, the "granularity" of combat calculations may also vary. Of course, rough and fine calculations are relative, so they cannot be simplified and grasped. As the saying goes, "what is suitable is the best". When grasping the "granularity" of combat calculations, the key to achieving appropriate thickness and appropriateness is to determine according to different levels, scenarios, stages, and needs. Roughly calculate goals, finely calculate indicators. The goal is the ultimate or phased state to be achieved in combat operations, which includes the responsible subject, target, time limit requirements, current state, future state, and relevance to the overall mission of the goal. The goal has macro guiding significance, is suitable for rough calculation, and tends to be qualitative. If it is too detailed, it will lead to a lack of focus, poor adaptability, and rigid execution. Indicators are specific scales for measuring the degree of achievement of goals, which can be said to decompose goals into outcome indicators and process indicators. The indicators are relatively specific and detailed, suitable for detailed calculation. If they are too coarse, it will lead to delayed and inaccurate target tracking, affecting the efficiency of target execution. Roughly calculate the total amount, finely calculate the allocation. The level of operational command varies, and the degree of precision in operational calculations also differs. The calculation by superiors is the total amount of tasks or resources, and when allocating downwards, guidance principles are emphasized in terms of tactics, time constraints, spatial areas, consumption limits, etc; Subordinates will refine the tasks or resources assigned by superiors to improve operability. So, as combat tasks or resources are gradually decomposed from coarse to fine, the calculation of "granularity" also evolves from coarse to fine. Roughly calculate the overall situation, finely calculate the key points. The overall combat situation contains numerous elements, each with different positions and functions, and is intricately linked to each other. This requires a general consideration at the overall level. If it is too detailed, it will not only be time-consuming and labor-intensive, but also lead to the complexity and confusion of global operations. The focus is on the most leveraged, urgent or core links in the overall situation, which require concentrated resources to break through. Focusing on the key points for deep and detailed calculations can improve the pertinence and timeliness of calculations, achieve the optimal path to promote global development, and achieve twice the result with half the effort. In short, combat calculation is the fundamental condition for operational planning. Grasp the "granularity" of combat calculations, on the one hand, we need to improve our sensitivity to data, have "numbers" in mind, and memorize various commonly used data and calculation formulas, proficiently master various calculation methods and tools; On the other hand, we should be good at using calculations to inspire wisdom, because no matter what kind of "granular" calculation, it cannot provide a "standard answer", nor can it replace human common sense, experience, imagination, adaptability, and intuition. Only by combining calculations with human unique creativity and complementing each other's advantages can we form the "strongest brain". (New Society)