1?2?3=4

It depends on the allowed operations between the digits 1, 2, and 3.

Possible solutions under common rule sets:

• If concatenation is allowed (treat 1 and 2 as 12): 12 ÷ 3 = 4.
• If exponentiation is allowed: 1^2 + 3 = 4.
• If you only allow +, -, ×, ÷ (no concatenation, no exponent): there is no way with exactly two operators to get 4.

Which rules should we assume for your problem? If you tell me, I can tailor the solution.