Question 30
Optional bonus: correct 20, incorrect −7, blank 0.
A teacher gives a paper strip of cells numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Step 1: choose one number from 2 through 9. Step 2: cut out its cell to separate the left and right strips. Step 3: multiply all numbers on each remaining strip, excluding the chosen number. Example: Manee chooses 5. The left product is 1 × 2 × 3 × 4 = 24; the right product is 6 × 7 × 8 × 9 × 10 = 30240. Mana follows these steps and obtains equal left and right products. Which number did he choose?
A teacher gives a paper strip of cells numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Step 1: choose one number from 2 through 9. Step 2: cut out its cell to separate the left and right strips. Step 3: multiply all numbers on each remaining strip, excluding the chosen number. Example: Manee chooses 5. The left product is 1 × 2 × 3 × 4 = 24; the right product is 6 × 7 × 8 × 9 × 10 = 30240. Mana follows these steps and obtains equal left and right products. Which number did he choose?