Grades 9-10 Video Solutions 2024-2024_9-10

Video Transcription

Video Summary

The problem involves finding a number \( n \) where the sum of its digits is three times the sum of the digits of \( n+1 \). This occurs when \( n \) ends in 9, causing the sum of \( n+1 \)'s digits to decrease by 8. By setting \( x = 3x - 8 \), we find the sum of the digits of \( n \) to be 12. Numbers like 39 fit this condition, as adding 1 reduces the digit sum by 8. Therefore, the smallest possible sum of the digits of such an \( n \) is 12.

Keywords

digit sum

number problem

mathematics

sum condition

digit reduction