"I haven't got my phone on me - I have no idea!" William replied.
"You guys will find out before I do at this rate."
The moment was captured by a fan who later posted the short video to Instagram.
The Duke of Cambridge visited New Zealand to meet with survivors of the terrorist attacks at Al Noor Mosque and Linwood Islamic Centre on March 15 which left 50 people dead and scores injured.
The Prince marked Anzac Day in Auckland by attending a commemoration at the War Memorial Museum with Prime Minister Jacinda Ardern.
Later, he visited the Starship Children's Hospital where he shared a touching moment with five-year-old Alen Alsati who was shot during the attack.
Meanwhile in the UK, fans continue to wait for news of the Sussexes' first born child.