Yes, Arithmetic serves a function. So does "Do unto others as you would have them do unto you." Feeding the hungry and clothing the naked also serve a useful function - and they are functions that cannot be performed by a ten-dollar calculator. The Sermon on the Mount certainly teaches people something useful. I learned Arithmetic and all those other things in a gentle, warm environment in Catholic schools, and not under any particular pressure. I also learned Critical Thinking in Catholic schools, and a good number of folk songs, and even the final three "Communist" verses to "This Land Is Your Land" that you most probably wouldn't hear in a public school (because they're too controversial and might upset somebody).