The question
Using the digits 1, 2, 3, and 4 just once each, insert operations to create an equation that equals 10.
Riddle lounge
Numbers in Line
Line up the digits carefully so the operations sing the right total.
Hints
Try grouping two digits first, then scale by the remaining ones. Brackets control how the math flows.
Answer
One solution is 4 × (3 − 1) + 2 = 10. We used each digit once, wrapped 3−1 in parentheses to make 2, and multiplied by 4 before adding the leftover 2.