Which among 432 , 672 , 522 , 592 would end with digit 1?
(a) 432
(b)672
(c)522
(d)592
(d) We know that, the unit's digit of the square of a natural number is the unit's digit of the
square of the digit at unit's place of the given natural number.
$\therefore$ Unit's digit of $43^{2}=9 \quad\left[\because 3^{2}=9\right]$
Unit's digit of $67^{2}=9$ $\left[\because\right.$ unit's digit of $7^{2}$ is 9$]$
Unit's digit of $52^{2}=4$ $\left[\because 2^{2}=4\right]$
Unit's digit of $59^{2}=1$ $\left[\because\right.$ unit's digit of $9^{2}$ is 1$]$
Clearly, the square of 59 end with digit $1 .$
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