[Home](./index.md) > [bitburner](./bitburner.md) > [HacknetNodesFormulas](./bitburner.hacknetnodesformulas.md) > [coreUpgradeCost](./bitburner.hacknetnodesformulas.coreupgradecost.md) ## HacknetNodesFormulas.coreUpgradeCost() method Calculate cost of upgrading hacknet node cores. **Signature:** ```typescript coreUpgradeCost(startingCore: number, extraCores?: number, costMult?: number): number; ``` ## Parameters

Parameter	Type	Description
startingCore	number	starting cores
extraCores	number	_(Optional)_ amount of cores to purchase (defaults to 1)
costMult	number	_(Optional)_ player cost reduction (default to 1)

**Returns:** number The calculated cost.