Question

1 Find the odd one out:
(a) 15
(b) 21
(c) 63
(d) 81
the answer is 81 but explain it how​

Answer 1

when ,u will add the units of all numbers u will observe -

a)5+1=6

b)2+1=3

c)6+3=9

d)8+1=9

so ,the option C and D have the same and only answer offer their addition that's why last number is been given the crown of odd man out