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Grade 12Discuss with colleagues and IITians

let N be natural number first digit (fromleft)is removed then natural number reduces to N/57 then sum of digits of N is ...................................... plz help me i have tried just give me some hint i will do it

Profile image of siva chava
15 Years agoGrade 12
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1 Answer

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ApprovedApproved Tutor Answer1 Year ago

To tackle this problem, let's break it down step by step. You have a natural number \( N \) from which the first digit is removed, and this new number is equal to \( N/57 \). The goal is to find the sum of the digits of \( N \). Here’s a hint to get you started:

Understanding the Relationship

When you remove the first digit from \( N \), you can express \( N \) in terms of its digits. Let's say \( N \) has \( d \) digits, and the first digit is \( a \). The number can be represented as:

  • N = a \times 10^{d-1} + M

Here, \( M \) is the number formed by the remaining \( d-1 \) digits. When you remove the first digit \( a \), you are left with \( M \). According to the problem, we know:

  • M = N/57

Setting Up the Equation

Now, substituting \( M \) back into the equation gives us:

  • M = (a \times 10^{d-1} + M) / 57

From this, you can rearrange the equation to isolate \( M \) and express it in terms of \( a \) and \( d \). This will lead you to a relationship between \( a \), \( d \), and \( M \).

Finding the Sum of the Digits

Once you have \( M \) in terms of \( a \) and \( d \), you can find \( N \) and subsequently the sum of its digits. The sum of the digits of \( N \) can be expressed as:

  • Sum of digits = a + (sum of digits of M)

To find the sum of the digits of \( M \), you can analyze the digits of \( M \) based on its value. Remember, since \( N \) is a natural number, \( a \) must be a digit from 1 to 9, and \( M \) must be a non-negative integer.

Next Steps

Now that you have the framework, try substituting values for \( a \) and \( d \) to find possible values for \( N \). This will help you calculate \( M \) and ultimately the sum of the digits of \( N \). Good luck, and remember to check your calculations as you go along!