Which of the following expressions are equivalent to (-19 + 3) - 6?
2 answers:
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Answer:
(a) 900
(b) 648
(c) 180
(d) 600
Step-by-step explanation:
If there are no restrictions, there are 10 possible values for each digit of a three-digit number.
(a) The leading digit cannot be zero
There are 9 options for the first digit and 10 for the remaining digits.
(b) The leading digit cannot be zero and no repetition of digits is allowed.
(c) The leading digit cannot be zero and the number must be a multiple of 5.
If a number is a multiple of five, it must end in 0 or 5
(d) The number is at least 400.
If the number is at least 400, the first digit can only be 4, 5, 6, 7, 8 or 9. There are no restrictions for the remaining digits.