How many perfect squares less than 1000 end with the digit 5?
4 answers
500?
Btw i changed my name but idk i think its division or subtraction idk
they will be of the form (5n)^2 where n is odd, so n = 2k+1
That makes them of the form (10k+5)^2 where 10k+5 < √1000
so now we have
10k+5 < 31
10k < 36
k < 3
So the only perfect squares less than 1000 and ending in 5 are
5^2 = 25
15^2 = 225
25^2 = 625
That makes them of the form (10k+5)^2 where 10k+5 < √1000
so now we have
10k+5 < 31
10k < 36
k < 3
So the only perfect squares less than 1000 and ending in 5 are
5^2 = 25
15^2 = 225
25^2 = 625
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1 answer