{"code":1,"error":null,"data":{"join":0,"list":[{"id":67323,"uid":637565,"username":"白芥","avatar":"https://img-avatar.eduzhixin.com/avatar/da074d0d31b0f1366b5396b33d55f973/s.jpg?x-oss-process=style/avatar\u0026t=202609122212","title":"有效数字的保留","content":"\u003cp\u003e本帖发出来是防止fw芥那天（比如今天）突然忘记了这个基础知识还没地方找...\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003e有效数字的保留规则：\u003c/p\u003e\u003cp\u003e1. 加减法：结果的小数位数与参与运算的数中小数位数最少的相同。\u0026nbsp;\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u0026nbsp; \u0026nbsp;例如：12.34 + 1.2 = 13.5（保留一位小数）\u003c/p\u003e\u003cp\u003e2. 乘除法：结果的有效数字位数与参与运算的数中有效数字最少的相同。\u0026nbsp;\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u0026nbsp; \u0026nbsp;例如：2.5 × 3.42 = 8.6（保留两位有效数字）\u003c/p\u003e\u003cp\u003e3. 常数和精确值：如 π、e 或定义值（N$A$），不影响力学计算的有效数字。\u003c/p\u003e\u003cp\u003e4. 对数（pH）：有效数字由小数部分决定。例如 pH = 3.45 有两位有效数字。\u003c/p\u003e\u003cp\u003e5. 中间步骤：保留多一位数字，最后再四舍五入。\u003c/p\u003e\u003cp\u003e6. 零的处理：\u003c/p\u003e\u003cp\u003e\u0026nbsp; \u0026nbsp;- 前导零（如 0.005）不是有效数字。\u003c/p\u003e\u003cp\u003e\u0026nbsp; \u0026nbsp;- 中间零（如 305）是有效数字。\u003c/p\u003e\u003cp\u003e\u0026nbsp; \u0026nbsp;- 末尾零是否有效需看表达方式：350 可能只有两位，350. 或 3.50×10² 表示三位。\u003c/p\u003e\u003cp\u003e7. 科学计数法：推荐使用，以明确有效数字。例如 4.5×10⁻³ 有两位有效数字。\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","channel_name":"化学","channel_id":3,"tags":"","thumb_up_num":9,"reply_num":2,"roof_placement":0,"last_comment_username":"","last_comment_time":1779292703,"has_thumb_up":0,"last_comment_at":"2026-05-20T15:58:23Z","is_del":0,"del_operater":0,"del_operater_name":"","create_time":"2026-05-19T14:41:21Z","labels":null,"problem_id":0,"updated_at":1779292703,"show_num":272,"other_params":"","essence":0,"special_topics":null,"special_topic_top":0,"zhixin_welcome":0,"fence":0,"fence_name":"全部","client_ip":"223.106.5.240","collection_num":5,"has_collect":0,"avatar_dress_up_url":"","avatar_dress_up_name":"","avatar_dress_up_id":0,"publisher":637565,"user_code":"UID_e3234ef5c0d57a9a03631a430edf0c25","is_ad":false,"ad_info":null,"unique_id":""}],"my_discuss_num":0,"my_reply_num":0,"thumb_up_num":0,"total":1}}