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Re: How many different twodigit positive integers are there [#permalink]
22 Feb 2018, 17:39
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answer: D integers are positive and two digits like 17, 68, 97, etc. in the two digits positive integers tens digit is the one with power 1, in the 17: tens digit is 1. In the 68: tens digit is 6. The question wants numbers which their tens digit is more than 6, Thus their tens digit can be 7, 8 and 9. Units digit is the digit with power 0, in 17: unit digit is 7, in 68: unit digit is 8. Unit digit must be less than 4, So it can be 0, 1, 2, 3. So we can have 7,8,9 in the tens digit and 0,1,2,3 in the unit digit. Possible numbers are: 70, 71, 72, 73 80, 81, 82, 83 90, 91, 92, 93 there are 12 numbers with these circumstances. *unit digit is the digit with power 0, tens digit is the digit with power 1, etc.
