90chain是多少m？
90chain = 1,810.512m
是1,810.512m，所以说成1,811m也没问题——四舍五入的误差在0.5%以内。
反过来，90m是多少chain？
90m = 4.4739chain
计算公式: m = chain × 20.1168
该数值前后的 chain → m
45 chain905.256m
50 chain1,005.84m
55 chain1,106.424m
60 chain1,207.008m
65 chain1,307.592m
70 chain1,408.176m
75 chain1,508.76m
80 chain1,609.344m
85 chain1,709.928m
90 chain1,810.512m
95 chain1,911.096m
100 chain2,011.68m
105 chain2,112.264m
110 chain2,212.848m
115 chain2,313.432m
120 chain2,414.016m
125 chain2,514.6m
130 chain2,615.184m
135 chain2,715.768m
140 chain2,816.352m