You see here a lock made by the Simplex Company. They advertise "thousands of combinations." Are they telling the truth? A combination is a sequence of 0-5 pushes. The pushes must follow these rules: You can push any number of buttons, from 0 to 5 Once a button is pushed, it stays in (so it cannot be re-used in a later push). Some possible combinations: {1 2 3} {4 5} (push 1, 2, 3 together, then push 4 and 5 together) {4 5} {1 2 3} (the order of pushes counts, but the order inside a push doesn’t) {1}{3}{4, 5} (you don’t have to use every button) {1 2 3 4 5} (push all the buttons at the same time) {1} {3} {2} {5} {4} (using all five buttons in five pushes) {} (no combination; the door is unlocked) Making Mathematics Home | Mathematics Projects | Students | Teachers | Mentors | Parents | Hard Math Café | Simplex Lock Project Description | Prerequisites | Warm Up Problems | Hints | Resources | Teaching Notes | Extensions | Results |
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