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Grade 12Algebra

2 to the power 405 divided by 7 then what is the quotient and remainder

first u have to find 2 to the power 405=? find the value

Profile image of keshav kr
14 Years agoGrade 12
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3 Answers

Profile image of Swapnil Saxena
14 Years ago

If u need to find the remainder the remainder , theres no need to evaluate 2^405 , this can be solved in the following ways.

2405 = (8)135=(7+1)135

Binomially expand the above expression as

= 135C07135+135C17134+135C27133+...+135C13471+135C13570

= In the above expansion, all the terms are divisible by 7 (They consist of 7 as a factor)

= Only 135C135 70 = 1 is non divisible as such 1 is the remainder

If you wanna find the quotient  try logarithm

2405= antilog(405 log2) , it will give u a fair approx. values

Quotient = antilog(405*log2 - log7 )

Profile image of Sathya
14 Years ago

The remainder is 1....................

Profile image of Sathya
14 Years ago

2^405 mod 7

 

(2^5)^81 ?mod7

 

(4)^81 mod7

 

(4^3)^27 mod7

 

(1)^27 mod 7

 

1 mod7

 

Therefore remainder is 1............