Question

What will be the unit digit of the squares of the following numbers?
$\left(i\right)81\left(ii\right)272\left(iii\right)799\left(iv\right)243\left(v\right)26387\left(vi\right)52698\left(vii\right)2796\left(viii\right)55555$

Answer 1

(i) $\because 1\times 1=1$

$\therefore$ The units digit of $(81{)}^2$ will be $1$

(ii) $\because 2\times 2=4$

$\therefore$ The unit digit of $(272{)}^2$ will be $4$

(iii) Since $9\times 9=81$

$\therefore$ The unit is digit of $(799{)}^2$ will be $1$

(iv) Since $3\times 3=9$

$\therefore$ The units digit of $(3583{)}^2$ will be $9$

(v) Since $4\times 4=16$

$\therefore$ The units digit of $(1234{)}^2$ will be $6$

(vi) Since $7\times 7=49$

$\therefore$ The units digit of $(26387{)}^2$ will be $9$

(vii) Since $8\times 8=64$

$\therefore$ The units digit is $(52698{)}^2$ will be $4$

(viii) Since $0\times 0=0$

$\therefore$ The units digits of $(99880{)}^2$ will be $0$

(ix) Since $6\times 6=36$

$\therefore$ The units digit of $(12796{)}^2$ will be $6$

(x) Since $\times 5=25$

$\therefore$ Units digit of $(55555{)}^2$ will be $5$