Question

$2630870$

Answer 1

Here the rule which is applicable on the series: 2 6 30 870 is rule D: Subtract the number from its square as:
$2^2$ $-2=2$,
$3^2$ $-3=6$,
$6^2$ $-6=30$ and
${30}^2$ $-30=870$
Hence, rule (D) is the correct answer