Property 'divmod' does not exist on type 'BN'

[tungleanh92]

export const toUnit = async (balance: any) => {
let curConfig: Config = getConfig();
const api = await setupProviderApi(curConfig);
let decimals = api.registry.chainDecimals;
let base = new BN(10).pow(new BN(decimals));
//I'm using typescript and it return the error at this line
let dm = new BN(balance).divmod(base);
return parseFloat(dm.div.toString() + "." + dm.mod.toString())
}
How can I fix this?