There are 24 different four-digit integers than can be
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16 Sep 2020, 20:03
Concept: Digit Notation --- for example, the Number 9, 450 can be written as =
9 * (1, 000) + 4 * (100) + 5 * (10) + 0 *(1) = 9, 450
Using this Concept and going through Digit by Digit:
In the Thousands Place:
Each Digit will appear 6 Times in the THOUSANDS PLACE throughout the 24 Arrangements of the Numbers:
6 * (2,000) + 6 * (3, 000) + 6 * (4, 000) + 6 * (5, 000) =
6 * (2,000 + 3, 000 + 4, 000 + 5, 000) =
6 * (14, 000) =
84, 000
in the HUNDREDS PLACE, the Same Pattern will occur with Each Digit appearing 6 times in the Hundreds Place:
6 * (200) + 6 * (300) + 6 * (400) + 6 * (500) =
6 * (1, 400) =
8, 400
In the TENS PLACE, following the Same Pattern:
840
In the UNITS PLACE:
84
84, 000 + 8, 400 + 840 + 84 = 93, 324
Answer -E-