Find the squares of the following numbers using the identify 
:
(i) 405
(ii) 510
(iii) 1001
(iv) 209
(v) 605
(i) 405
We have,
(405)2 = (400 + 5)2
= (400)2 + 52 + 2 (400) (5)
= 160000 + 25 + 4000
= 164025
We have,
(510)2 = (500 + 10)2
= 250000 + 100 + 10000
= 260100
We have,
(1001)2 = (1000 + 1)2
= (1000)2 + 1 + 2 (1000)
= 1000000 + 1 + 2000
= 1002001
We have,
(209)2 = (200 + 9)2
= (200)2 + 92 + 2 (200) (9)
= 40000 + 81 + 3600
= 43681
We have,
(605)2 = (600 + 5)2
= (600)2 + 52 + 2 (600) (5)
= 360000 + 25 + 6000
= 366025
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