solidity百分比乘法

Right, Solidity only supports integers. Try this instead:

uint sales = 100;
uint afterCommission = sales * 5 / 100; // 5%

If it’s a variable amount but a whole number percent:

uint commissionPercentage = 7;
uint afterCommission = sales * commissionPercentage / 100; // 7%

If you need more decimal places:

uint commissionNumerator = 75;
uint commissionDenominator = 1000;
uint afterCommission = sales * commissionNumerator / commissionDenominator; // 7.5%

https://ethereum.stackexchange.com/questions/41616/assign-decimal-to-a-variable-in-solidity