CashPoints are earned based on the net ticket price (excl. taxes, charges and optional services). Earning CashPoints on flights is personal, so you are only entitled to earn CashPoints on your own flights.
500 CashPoints will get your from London to Rome
With only 500 CashPoints you can fly from London to Rome.
Of course the price of your ticket depends on when you book. Seats are limited.
Remember you can use your CashPoints on all flights and all destinations with Norwegian.