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177 problems, every one written from scratch, every wrong answer carrying the mistake that produces it. 708 explanations in all.
177 problems
Four road signs are shown. Exactly one of them has two lines of symmetry. Which one is it?
On the number line shown, the marks are equally spaced. What number does the arrow point to?
The four-digit number 27_4 is divisible by 3. Which digit could go in the gap?
How many two-digit numbers have digits that add up to 8?