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Smart Contract Precision Handling Best Practices

Use Sufficient Precision Factor

Choose a precision factor large enough to handle small decimal values:

// Use higher precision instead of standard 1e18
uint256 private constant PRECISION = 1e24;

Avoid Direct Division

Always multiply before dividing to prevent precision loss:

// Incorrect - Precision loss due to early division
uint256 result = (amount * rate) / precision;
// Correct - Multiply by precision factor first, then divide
uint256 result = (amount * rate * PRECISION) / (precision * PRECISION);

Maintain Consistent Precision Handling

Apply the same precision calculation pattern throughout the contract:

// Reward calculation example
uint256 rewardPerShare = (reward * PRECISION * PRECISION) / (totalStaked * PRECISION);
uint256 pending = (userStakeAmount * accRewardPerShare * PRECISION) / (PRECISION * PRECISION);

Example

contract Example {
    uint256 private constant PRECISION = 1e24;
    function calculateReward(uint256 amount, uint256 rate) public pure returns (uint256) {
      // First multiply by precision factors
      uint256 preciseAmount = amount * PRECISION;
      uint256 preciseRate = rate * PRECISION;
      // Then perform division
      return (preciseAmount * preciseRate) / (PRECISION * PRECISION);
  }
}