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177 problems, every one written from scratch, every wrong answer carrying the mistake that produces it. 708 explanations in all.
36 problemsClear all filters
Red and blue counters are in the ratio 3 to 5. There are 40 counters altogether. How many are red?
A sequence starts 4, 7, 10, 13 and continues in the same way. What is the 20th term?
What is the remainder when 2 to the power 30 is divided by 7?