Some chapters on INKR require coins to unlock.
1. Open any Coin-chapter (These chapters have the Coin icon on the top left of its thumbnail).
2. At the end of the chapter preview, you can find the options to unlock a single chapter, or multiple chapters with Coins.
Bulk Discount for unlocking multiple chapters
INKR Extra members get bulk discount for any purchase over 20 coins.
The discount percentage depends on the number of chapters you selected and the number of Bonus coins in your wallet.