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How many integers between 500 and 1000 contain both the digits 3 and 4?

 Dec 27, 2021
 #1
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They are all 3-digit numbers, so I'm going to put three lines to represent the three digits in the number.

 

 

___ ___ ___

 

 

The first digit has five possible options: 5, 6, 7, 8, 9

The second digit has two possible options: 3, 4

The third digit uses the remaining number from the second space: either 3 or 4;;; 1 option

 

_5_  _2_  _1_

 

We multiply these together to get 5 * 2 * 1 which is equal to 10 numbers

 

(if you want, you can list them out as well. they are 534  543  634  643  734  743  834  843  934  943)

 

 

- h

 Dec 27, 2021

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