(i) Subtraction: 6237 − 694 = 5543
Addition: 5543 + 694 = 6237
(ii) Subtraction: 21205 − 10899 = 10306
Addition: 10306 + 10899 = 21205
(iii) Subtraction: 100000 − 78987 = 21013
Addition: 21013 + 78987 = 100000
(iv) Subtraction: 1010101 − 656565 = 353536
Addition: 353536 + 656565 = 1010101