what is the common digit while count from 9 to 1
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Answer:
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How many times does the digit 9 appear while counting from 1 to 100?
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Anuj Sikarwar
Answered September 9, 2018
SORRY FOR THE MESSY SOLUTION , BUT I HOPE YOU WILL UNDERSTAND WHAT I HAVE DONE !
SIMPLE BREAK THE QUESTION INTO 3 CASES
CASE 1 : UNIT DIGIT IS 9 , WHICH THE THE SOLUTION ITSELF
CASE 2: A DOUBLE DIGIT NUMBER HAVING UNIT DIGIT 9 AND DISTRIBUTE ANY NUMBER FROM 0 TO 9 TO THE SECOUND DEGIT
CASE 3: DOUBLE DIGIT NUMBER WITH TENTH DIGIT 9 , now this is the tricky part ! As you have to decide the number that you can put in unit digit , 0 and 9 will not be included as when you put 0 the ans will be same as CASE 1 and when you put 9 you will get 99 twice (1 in CASE2 AND NOW IN CASE 3)
THIS IS A NICE METHOD , I WOULD NOT ADVISE YOU TO SIMPLE COUNT THE NUMBER LIKE ONE HAS DONE IN THE PREVIOUS ANSWER BECAUSE IN PAPER QUESTION WILL BE LIKE find number of digits between 500–5000 having 9 as a digit !
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