The smallest 5 digit number is 10000 = 1002
The largest 5 digit number is 99999 and 3162 < 99999 < 3172
So, take any number between 100 and 316 (both inclusive) and square it to get a 5-digit perfect square.
There are 5 numbers which can make the 3 digit numbers in this example. Therefore each digit in the 3 digit number has 5 choices of which number can be placed there. Therefore number of 3 digit numbers = 5 x 5 x 5 = 125
Not sure what a "didget" is. It is possible to make 18 5-digit numbers.
8
about... 25 just take 5 numbers times 5 numbers
There are 600 5-digit numbers divisible by 150.
There are 5 numbers which can make the 3 digit numbers in this example. Therefore each digit in the 3 digit number has 5 choices of which number can be placed there. Therefore number of 3 digit numbers = 5 x 5 x 5 = 125
Not sure what a "didget" is. It is possible to make 18 5-digit numbers.
8
about... 25 just take 5 numbers times 5 numbers
The first digit can be any one of 1,2,3,4,5. With each choice of digit1, the second digit can be any one of 1,2,3,4,5 so making 5*5 two-digit numbers. With each of these, the third digit can be any one of 1,2,3,4,5 so making 5*5*5 three-digit numbers and so on. The total number is 55 = 3125.
2
There are 600 5-digit numbers divisible by 150.
The largest 5 digit perfect square is 99856 = 3162
12689 14689 12489
90
There are 5*4*3 = 60 such numbers.
There are five such numbers.