3.The squares of which of the following would be odd numbers?
(i) 431

(ii) 2826

(iii) 7779

(iv) 82004

The squares of a number would be odd number depending upon the unit's digit of the number.If the number has an even unit digit then it will have an even square number and if the unit's digit is odd then it will have an odd square number.Here we have:
(i) \(431^2\) is an odd number as the unit's digit is odd.

(ii) \(2826^2\) is an even number as the unit's digit is even.

(iii) \(7779^2\) is an odd number as the unit's digit is odd.

(iv) \(82004^2\) is an even number as the unit's digit is even.