[Home](./index.md) > [bitburner](./bitburner.md) > [HacknetServersFormulas](./bitburner.hacknetserversformulas.md) > [coreUpgradeCost](./bitburner.hacknetserversformulas.coreupgradecost.md) ## HacknetServersFormulas.coreUpgradeCost() method Signature: ```typescript coreUpgradeCost(startingCore: number, extraCores?: number, costMult?: number): number; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | startingCore | number | | | extraCores | number | | | costMult | number | | Returns: number