Start with the numbers 1,2,3,4,5,6,7,8,9,10 in that order and use the four common operations (+ − × ÷) and number concatenation (ie, you may write 123 concatenating 1, 2, 3) to obtain 2020.
- All the ten numbers must be used, in that order, without repetitions.
- Unary - is allowed; inserting decimal point is also allowed.
- Number 10 cannot be split as 1 0; it can of course be concatenated with 9 to obtain 910.
- Concatenation may only be applied to literal digits.
- Exponentiation is not allowed, even though it is written without any explicit operators.