
Corey G. answered 07/19/20
PhD in Computer Engineering with over 20 years of Experience
Gwen,
When a base is not specified explicitly (using a subscript), then the assumed base for arithmetic is base 10. This is because humans have 10 fingers (normally), and fingers were one of the original calculating/counting tools (this is why fingers are called digits). Thus, base 10 is called the common base, and there is no need to explicitly specify it with a subscript (but you can if you want to). Below are the results of 2 + 2 in bases from 2 up to 10. Notice that as long as the the base is greater than the quantity of the result (4), then the the quantity can be represented by the digit "4" in that base. This is because a particular base (base N) only has digits that range from 0 up to N-1.
102 + 102 = 1002
23 + 23 = 113
24 + 24 = 104
25 + 25 = 45
26 + 26 = 46
27 + 27 = 47
28 + 28 = 48
29 + 29 = 49
210 + 210 = 410