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We have to consider 2 cases:
When the hundreds digit is 3, we want the sum of the tens and unit digit equal to 13. We have 4+9=5+8=6+7=13, which yield a total of 6 choices (two for each pair that adds to 13).
When the hundreds digit is 4, we want the sum of the tens and unit digit equal to 12. We have 3+9=4+8=5+7=6+6=12. The first three pairs give us 2 solutions, but the last only gives 1, so we have a total of 7 choices.
Therefore there are total of 6+7=13 integers.
What else can I help you with?
How many positive integers ar equal to 12 times the sum of their digits?
There are none.
How many numbers between 10 an 30 have digits that have a sum of 5?
Two integers.
How many integers with distinct digits are there between 1000 and 9999 such that the absolute value of the difference between the first and the last digit is 1?
952 of them.
How many integers with distinct digits are there between 1000 and 9999 such that the absolute value of the difference between the first and the last digit is 3?
An infinite amount
How many significant figures are in 13.003?
Five. All nonzero integers are significant and zeros in between significant digits are significant.
How many odd integers between 1000 and 9999 have distinct digits?
There are 120 of them.
How many positive integers ar equal to 12 times the sum of their digits?
There are none.
How many odd integers between 1000 and 8000 have only non zero digits?
How many
How many positive integers less than 100 have the sum of their digits equal to a perfect square?
There are 20.
How many numbers between 10 an 30 have digits that have a sum of 5?
Two integers.
How many integers are there between 100 and 1000 all of whose digits are odd?
There are 125 of them.
How many integers between 1000-9999 have distinct digits?
9*9*8*7 = 4536
How many integers between 200 and 300 have the sum of their digits equal to 15?
Since the first integer of the 3-digit numbers must be 2, the sum of the second and the third digits would be 13.Since the largest digit is 9, the 3-digit numbers could be 249, 294, 258, 285, 267, and 276.Thus, there are 6 integers between 200 and 300 whose sum of their digits is 15.
How many digits positive integers does the products of the digit equal 20?
There are infinitely many. For example, consider, 45, 451, 4511, 45111, 451111 and so on.
How many integers with distinct digits are there between 1000 and 9999 such that the absolute value of the difference between the first and the last digit is 1?
952 of them.
How many integers with distinct digits are there between 1000 and 9999 such that the absolute value of the difference between the first and the last digit is 3?
An infinite amount
How many significant figures in 20012?
Five. All nonzero integers are significant and zeros in between significant digits are significant.
