Perhaps with your phone being able to remember 10-digit numbers for you, this leaves you and/or young people today with more mental space and energy to do more

Perhaps with your phone being able to remember 10-digit numbers for you, this leaves you and/or young people today with more mental space and energy to do more interesting mental tasks such as exploring recreational mathematics. And perhaps this is a general process when calculators, computers, phones, etc. automate activities which were mentally challenging (and so were good mental exercise) but ultimately not intellectually interesting?