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प्रश्न
How many 3-digit even number can be made using the digits 1, 2, 3, 4, 5, 6, 7, if no digits is repeated?
उत्तर
In order to find the number of even digits, we fix the unit's digit as an even digit.
Fixing the unit's digit as 2:
Number of arrangements possible = 6P2 = `6xx5=30`
Similarly, fixing the unit's digit as 4:
Number of arrangements possible = 6P2 = `6xx5=30`
Fixing the unit's digit as 6:
Number of arrangements possible = 6P2 =`6xx5=30`
∴ Number of 3-digit even numbers that can be formed = 30 + 30 + 30 = 90
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