Fing 1+11+111+1111+......upto n turms
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we will multiply and this with 9 so we get
1/9(9+99+999+9999+......n)
=1/9[(10-1)+(100-1)+(1000-9)+........n]
=1/9[10+100+1000+...n]-[1+1+1+....n]
=1/9[10(10^n-1)/10-1 - n]
=1/9[10(10^n-1)/9 - n]
=10/81[(10^n-1)-9n]
1/9(9+99+999+9999+......n)
=1/9[(10-1)+(100-1)+(1000-9)+........n]
=1/9[10+100+1000+...n]-[1+1+1+....n]
=1/9[10(10^n-1)/10-1 - n]
=1/9[10(10^n-1)/9 - n]
=10/81[(10^n-1)-9n]
RivenDost:
There is *divide after and
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