     +,-,*        ,        .          "" (.       ).

:

"5" * "5" = "25"

"4321" - "1234" = "3087"

"1234" * "4321" = "5332114" 

"12456789031415" + "98765432123456789" = "98777888912488204"

"12456789031415" * "98765432123456789" = "1230300151558439221348916026435"

.  /           (< 1000)          .