If is the greatest integer less than or equal to , what is the value of ?
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Thanks for this one! I initially tried to compute each floor value individually like an idiot until I realized the values repeat in blocks.
Same here lol. Once you see the pattern, it goes way faster.
Took me a second to spot it too. Grouping by perfect squares is the key.
Wait, how do you know which numbers give the same floor value? I get that floor(sqrt(1)) = 1 and floor(sqrt(4)) = 2, but I'm not sure how to count them efficiently without listing everything.
Think about when the floor changes: it jumps at perfect squares.
For each integer k, count how many n have floor(sqrt(n)) = k. That's the gap between consecutive squares.
Solid medium question. Got 217 after grouping by perfect squares and summing k times the count in each block. Definitely a time-saver if you spot the structure early.
Nice, I got the same. The block from 36 to 49 caught me off guard for a second though.
Yeah, 217 felt right. The trap answers are pretty close so you have to be careful with the counting.
Is there a shortcut formula for sums like this? Or do you just have to manually count the blocks each time? Feels like it could eat up time on test day.
There's a general pattern: sum of k*( (k+1)^2 - k^2 ) over the relevant k range. But honestly, counting blocks is fast enough here.
For 50 terms, block counting is probably quicker than deriving anything fancy.
What it tests
Your ability to evaluate and compose functions, including unusual defined operations.
Common trap
Applying function operations in the wrong order or ignoring domain restrictions.