This Sudoku variant supplies the correct triad locations of the numbers of the solved puzzle, but offers far fewer starting numbers. Even so, the puzzle is solvable when considering the subset of candidates that can be in a particular cell.
I found a math site called cut-the-knot.org that shows how you can intersperse only plus or minus signs to the fixed sequence of digits 1 2 3 4 5 6 7 8 9 so that the resulting arithmetic expression, when simplified, is 100. It’s both harder and easier than you think! Likewise, the sequence 9 8 7 6 5 4 3 2 1 is also considered for expressions results simplifying to 100. There’s more than one, but not many.