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TathaGat
@tathagat
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Topics: 0 / Replies: 18
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RE: Divisibility and Remainders

@mayanksri 111111.... (27 ) times 111 × 10^24 + 111 × 10^21 + 111 × 10^18 +...... +111 × 10^3 + 111 As 1000 = 10^3 ≡ 1 mod 999. ...

6 months ago
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RE: Divisibility and Remainders

@mayanksri ABCD – DBCA 1000A + 100B + 10C + D – ( 1000D + 100B + 10C + A) 999A – 999D 999( A-D) 999 is not divisible by 7 . so ( A – D) sho...

6 months ago
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RE: Divisibility and Remainders

@Mayank Sum of squares of first n natural number = n ( n +1 )( 2n +1 ) /6 so (1+2²+3²+....+49²) = 49 ( 50) ( 99)/6 .

6 months ago
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RE: Divisibility and Remainders

@mayanksri 12600= (2^3)* (3^2)*(5^2)*(7) powers of 2 in 50! by successive division = 50+25+12+6+3+1= 97, hence power of 2^3 will be 97/3 = 32same...

6 months ago
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RE: Unit Digits and Last Two Digits

@mayanksri 71.72.73.74.……………..72020 = 7(1 + 2+ 3+ ………….2020) =72020(2020+1)/2 = 71010 x 2021 When 1010 x 2021 is divided by 4 gives remainde...

6 months ago
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RE: Trailing Zeros

@mayanksri Please find the solution below, N = 4*8*12*....*1000 = (4*1)*(4*2)*(4*3)*.....*(4*250) = 4250*(1*2*3*...250) = 2500*250!Now 250! = 224...

6 months ago
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RE: Trailing Zeros

@mayanksri power of 5 in 100!*200!=73. Thus number of zeros at the end of this num = 73.

6 months ago
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RE: Trailing Zeros

@mayanksri Please find the solution below. 30! = 2^26 x 3^14 x 5^7 x 7^4 x 11^2 x 13^2 x 17^1 x 19^1 x 23^1 x 29^1 Now the for the first non ze...

6 months ago
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RE: HCF and LCM

@lydiamadini Please find the solutions below. 1. The LCM of the individual intervals will give the time at which all the bells will ring togethe...

6 months ago
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RE: Fractions

1.85 can be split into 1.000 1 +.500 1/2 +.25 1/4 +.1 1/10--------1.85 Hence 1+2+4+10=17

6 months ago
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RE: Factors and Multiples

Hello Anu, Since 7,8 and 9 are co-prime, the number which is divisible by 7,8 and 9, must also be divisible by their L.C.M i.e. by 504. Now let's ...

6 months ago
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RE: Factors and Multiples

Hello Anu Find the solution: 536 - 1 = 2518 - 1 = (24 + 1)18 - 1 = 2418 + 18 x 2417 + ... + 18 x 24 + 1 - 1 = 122k. OR 536 - 1 = (4 + 1)36 - 1...

6 months ago
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RE: Factors and Multiples

@anna Let a, b, c are the 3 digits of that number. a3 = (abc + 2), b3 = (abc - 3), c3 = (abc + 3). Multiply all three equations and keep abc = x....

6 months ago
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RE: Factors and Multiples

@anu 544 =25x17. Perfect squares divisors of 544 are: 1, 4, 16 Sum = 21

6 months ago
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RE: Factors and Multiples

96 = 25x3; Sum of even divisors of 96 = (21+22+23+24+25)(30+31) = 248= 3600=24x32x52; Sum of odd divisors of 3600 = (30+31+32)(50+51+52) = 403 Ans...

6 months ago
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