shaderon wrote:
Hello there
I tried using the following approach. I did end up taking some time.
The numbers to be considered are 2,3,5 &7.
For 2-digit numbers:
(4 PRIME numbers in the Ten's place)
(4 PRIME numbers in the Unit'splace)
4*4 = 16 ---(1)
For 3-digit numbers:
(9 numbers in the Hundred's place i.e 1 to 9)
(4 PRIME numbers in the Ten's place)
(4 PRIME numbers in the Unit's place)
9*4*4 = 144 ---(2)
For 4-digit numbers (till 1500):
(1 number in the Thousand's place i.e. 1)
(5 numbers
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