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Instructional Video5:28
Curated Video

"Prove" 3 = 0. Can You Spot The Mistake?

6th - 11th
Thanks to Lucas from Brazil who sent this problem! This is a proof that 3 = 0 using sneaky algebra that I had never seen before (this is a sneaky mistake, not a simple divide by 0 fallacy). Every step seems correct, but the conclusion is...
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Instructional Video2:54
Curated Video

Can You Solve The Number Of Children Riddle?

6th - 11th
Many people make mistakes in this seemingly routine algebra problem. The average age of a family (two parents and their children) is 20. If we exclude one parent, who is 40, the average age drops to 15. How many children are in the...