2+2

4

Note: In base-10 (decimal) arithmetic, 2 + 2 = 4. In other bases:

• Base 3: 2 + 2 = 11_3 (which is 4 in decimal)
• Base 4: 2 + 2 = 10_4 (which is 4 in decimal)
• Bases 5 and higher: 2 + 2 = 4 (the digit 4 exists)