All Sudoku puzzles are solvable only through logical deductions, with no guessing. Some hard Sudoku puzzles may require deductive techniques that you don't know.
Is Sudoku a logic puzzle?
"Sudoku is a puzzle with pure logic," Shortz says about the American invention. "It has a grid of 9-by-9 divided into nine 3-by-3 boxes. The object is to put the numbers into each box, row and column — there's no mathematics involved. All you have to do is know the numbers 1-9."
Does solving Sudoku mean you have a high IQ?
From this case study it can be concluded that an individual who is skilled at solving Sudoku puzzles likely has a high general IQ. The results of the weak correlation between Sudoku scores and the WAIT test indicates that in some cases a high Sudoku doesn't necessarily mean a high general IQ.