# expectedTradeInput()

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```solidity
    function expectedTradeInput(Token token, uint128 targetAmount) external view returns (uint128 sourceAmount);
```

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Using this function, one can query the contract indicating the target token amount they would like to receive, and receive an indication of the expected source token amount required. 

Note that since the rate changes over time, the required amount might reduce with time as the price changes.

### **Function Arguments**

<table><thead><tr><th width="162">Name</th><th width="114.66666666666663">Type</th><th>Description</th></tr></thead><tbody><tr><td>token</td><td>Token</td><td>The token address of the token you would like to trade out of the contract</td></tr><tr><td>targetAmount</td><td>uint128</td><td>The amount of target tokens you would like to receive at the end of the trade</td></tr></tbody></table>

### Example

{% code overflow="wrap" %}

```solidity
expectedTradeInput(
0x1f573d6fb3f13d689ff844b4ce37794d79a7ff1c, //token address
4027872880331900000000 //target amount indicated in wei
)
returns (
1000000000000000000 //the required amount of source tokens indicated in wei
)
```

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