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1st digit: 2 or 4; 2 waysGurpinder wrote:If the first and last digit must be a 2 or a 4, how many 5-digit numbers are possible?
2*10*10*10*1 = 2000 (which is the wrong answer)
what am i doing wrong?
Hey Rahul,Rahul@gurome wrote:1st digit: 2 or 4; 2 waysGurpinder wrote:If the first and last digit must be a 2 or a 4, how many 5-digit numbers are possible?
2*10*10*10*1 = 2000 (which is the wrong answer)
what am i doing wrong?
5th digit: 2 or 4; 2 ways
2nd digit: 0 to 9; 10 ways
3rd digit: 0 to 9; 10 ways
4th digit; 0 to 9; 10 ways
No. of 5 digit nos. that are possible = 2*2*10*10*10 = 4,000
Gurpinder, it is not mentioned in the question that the digits 2 and 4 cannot be repeated, which means repetition of digits is allowed. Does that answer your query?Gurpinder wrote:
Hey Rahul,
Thanks for the reply. But I have a question. I understand that the 1st digit has 2 options. But then wouldnt the last digit have 1 option left because 1 of those 2 options has already been selected for the 1st digit. so theres only one option left for the last one.?
Ahh... Thank you!Rahul@gurome wrote:Gurpinder, it is not mentioned in the question that the digits 2 and 4 cannot be repeated, which means repetition of digits is allowed. Does that answer your query?Gurpinder wrote:
Hey Rahul,
Thanks for the reply. But I have a question. I understand that the 1st digit has 2 options. But then wouldnt the last digit have 1 option left because 1 of those 2 options has already been selected for the 1st digit. so theres only one option left for the last one.?
Welcome!Gurpinder wrote:
Ahh... Thank you!
