Clearly, The given numbers are not in the decimal system. the maximum digit we have in the given numbers is 7. So, the possible number system would be base > = 8(Octal).
In Octal the digits range from 0 to 7. the numbers in octal system are 0,1,2,3,4,5,6,7,10,11,12,13,14,15,16,17,20,21,......
first, the given numbers: 453 + 746 = 1421
3 + 6 = 9 (in decimal ) equivalent in octal = 11 (2nd number after digit 7) :
sum = 1, carry = 1
5 + 4 + 1 (carry) = 10 (in decimal) equivalent in octal = 12 (3rd number after 7)
sum = sum = 21, carry = 1
4 + 7 + 1(carry) = 12 (in decimal) equivalent in octal = 14 (5th element after 7)
sum is 1421
similarly, 346 + 521 :
6 + 1 = 7
4 + 2 = 6
3 + 5 = 8 (in decimal) equivalent in octal = 10
sum is 1067.
correct me if any wrong in explanation.
