Digits (0,1,2,3,4,5,6) से repetition बिना (4)-digit numbers बनाने हैं जो (5) से divisible हों। सही count expression कौन-सा है?
Using digits (0,1,2,3,4,5,6) without repetition, (4)-digit numbers divisible by (5) are formed. Which count expression is correct?
Explanation opens after your attempt
Correct Answer
A. \(6\cdot5\cdot4+5\cdot5\cdot4\)
Concept
The last digit can be (0) or (5), and (0) changes the first-digit restriction. In exams make unit-digit cases for divisibility by (5).
Why this answer is correct
The correct answer is A. \(6\cdot5\cdot4+5\cdot5\cdot4\). The last digit can be (0) or (5), and (0) changes the first-digit restriction. In exams make unit-digit cases for divisibility by (5).
Exam Tip
Last digit (0) या (5) हो सकता है, और (0) first digit पर restriction बदलता है। परीक्षा में divisibility by (5) में unit digit cases बनाएं।
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