Question
Using divisibility tests, determine if the number $31795072$ is divisible by
$a.\ 4$
$b.\ 8$
$a.\ 4$
$b.\ 8$
✓
Answer
$i.\ $Divisibility by $4.$
The number formed by last two digits $= 72$
$\text { (4) } 72(18)$
$\frac{4}{32}$
$\frac{32}{0}$
$\because$ Remainder is $0.$
$\therefore 72$ is divisible by $4.$
$\therefore 31795072$ is divisible by $4$ because a no. is divisible by $4$ if the no. formed by its last two digits is divisible by $4.$
$ii.\ $Divisibility by $8.$
The number formed by last three digits $= 072 = 72$
$(8) 72(9)$
$\frac{72}{0}$
$\because$ Remainder is $0.$
$\therefore 72$ is divisible by $8$.
$\therefore 31795072$ is divisible by $8$ because a no. is divisible by $8$ if no. formed by its last three digits is divisible by $8.$
The number formed by last two digits $= 72$
$\text { (4) } 72(18)$
$\frac{4}{32}$
$\frac{32}{0}$
$\because$ Remainder is $0.$
$\therefore 72$ is divisible by $4.$
$\therefore 31795072$ is divisible by $4$ because a no. is divisible by $4$ if the no. formed by its last two digits is divisible by $4.$
$ii.\ $Divisibility by $8.$
The number formed by last three digits $= 072 = 72$
$(8) 72(9)$
$\frac{72}{0}$
$\because$ Remainder is $0.$
$\therefore 72$ is divisible by $8$.
$\therefore 31795072$ is divisible by $8$ because a no. is divisible by $8$ if no. formed by its last three digits is divisible by $8.$
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