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by kccqzy 665 days ago
That's not how cardinality is measured. The very first class on an introduction to set theory course will teach you that bijections are used to measure the size of a set.

Consider the tan function. When you give it a number between 0 and pi/2, it gives you a number between 0 and infinity, and it does so in a bijective way. Therefore there are equal numbers between 0 and pi/2 as compared to 0 to infinity. Now consider a simple linear function that multiplies its input by pi/2. From here we know that there are equal numbers between 0 and 1 as compared to 0 and pi/2.