Question:
From the digits 1, 2, 3, 4, 5, 6, how many natural digits less than 100 can be formed?
Reference explanation:
Correct Answer: EASY
Numbers less than 100 are one- and two-digit numbers formed from the set A = {1, 2, 3, 4, 5, 6}.
From set A it is possible to form 6 single-digit numbers.
Call a two-digit number of the form ab with (a, b) ∈ A.
Inside:
a is selected from the set A (with 6 elements), so there are 6 ways to choose.
b is selected from the set A (with 6 elements), so there are 6 ways to choose.
Thus, we have 6.6 = 36 two-digit numbers.
So, from A it is possible to form 6 + 36 = 42 natural numbers less than 100.
Choose the EASY answer
ADSENSE
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