Question

A suitcase has a lock on it consisting of four numbers. Each number could be any number 0-9. The only restriction is that the last slot has to be an even number. How many possible combinations for the lock

Answer 1

The suitcase has a lock consisting of four number.

Each number could be any number from 0 to 9.

for each of the first three numbers slot on the lock, there are 10 possible numbers that can fit in (that is 0,1,2,3,4,5,6,7,8,9)

And for the last slot, According to the restriction given in the question that it has to be an even number.

So, for the last slot the possible numbers that can fit in are (0,2,4,6,8), which are even numbers between 0 and 9. which means there are 5 possible numbers for the last slot.

The total number of possible combinations is equal to the product of the number of possible numbers for each slot.

`N\text{ }=\text{ N1 }*\text{ N2 }*\text{ N3 }*\text{ N4}`

Where N is the total number of possible combination for the slot, and N1,N2,N