SOLUTION: How many positive integers less than 6000 may be written down without using the digits 6,7,8,9 and 0? Thank you so much

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Question 857969: How many positive integers less than 6000 may be written down without using the digits 6,7,8,9 and 0?
Thank you so much
Answer by Edwin McCravy(20054)   (Show Source): You can put this solution on YOUR website!
We can only use the digits 1,2,3,4, and 5

Number of 1-digit positive integers:

Pick the digit any 5 ways

That's 5 1-digit positive integers

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Number of 2-digit positive integers:

Pick the first digit any of 5 ways.
Pick the second digit any of 5 ways.

That's 5×5 or 52 2-digit positive integers.

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Number of 3-digit positive integers:

Pick the first digit any of 5 ways.
Pick the second digit any of 5 ways.
Pick the third digit any of 5 ways

That's 5×5×5 or 53 3-digit positive integers.

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Number of 4-digit positive integers:

Pick the first digit any of 5 ways.
Pick the second digit any of 5 ways.
Pick the third digit any of 5 ways.
Pick the fourth digit any of 5 ways

That's 5×5×5×5 or 54 4-digit positive integers.

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Total = 5+52+53+54 = 5+25+125+625=780

Edwin
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