Answer:The missing number is 27
Step-by-step explanation:It is a matter of spotting the relationship if you can. If not obvious you will need to experiment to find what type of sequence it is; geometric or arithmetic.
Observe that there is a connection of 3 in the numbers 1,3,9 in that
1
×
3
=
3
Lets experiment with that for a moment!
If we apply the same rule to 3 what will we get?
3
×
3
=
9
which is correct.
Ok. lets apply the same rule yet again!
9
×
3
=
27
Using 27, if we apply the rule once more and get 81 we have found the correct 'rule' for this sequence.
27
×
3
=
81
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This works so the missing number is 27