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Zatarra
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mundasingh123
Hi Bunuel i have 7 posts stuck in my mail box .so, i thiught of this way . Yea i know its not there but i just thought that since u r a math wixz u might be knowing this concept

I'm aware of it but I've never used it when solving GMAT problems, so wouldn't worry about it at all.
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ha ha - i looved this conversation

Munda Singh - i like your enthusiasm
Bunuel - i like how you keep it simple, no-nonsense and to the point! i have a sneaky feeling you'll ace the gmat if you were (is subjunctive mood correct here?) to ever try...
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gmat1011
ha ha - i looved this conversation

Munda Singh - i like your enthusiasm
Bunuel - i like how you keep it simple, no-nonsense and to the point! i have a sneaky feeling you'll ace the gmat if you were (is subjunctive mood correct here?) to ever try...
On a lighter note, My enthu is so high , had i a trampoline i would have broken it by jumping , but still i wudnt have come up to bunuels level.
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Im not sure i got it.

Can someone plz give a full detailed explanation?

thanks.
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144144
Im not sure i got it.

Can someone plz give a full detailed explanation?

thanks.

Consider all the possible numbers that we can form using 9 & 16. To make this easier split them into different sets, according to the remainder they leave with 9 :

1) Remainder 0 : These are divisible by 9. And all of these can be formed by using 9 alone
2) Remainder 1 : The number is of the form 9x+1. We need 9x+1=9a+16b where a & b are non-negative integers. In other words we need, 16b=9(x-a)+1. The smallest b for which this happens is 4. 16x4=64=9x7+1
Hence, the smallest such number possible is 64, then 64+9, 64+18, 64+27, ... and so on
So all numbers of the form 9k+1, greater than or equal to 64 can be formed by 9s and 16s
3) Remainder 2 : Similar logic applies ... smallest number is 128
4) Remainder 3 : Smallest number is 48
5) Remainder 4 : Smallest number is 112
6) Remainder 5 : Smallest number is 32
7) Remainder 6 : Smallest number is 96
8) Remainder 7 : Smallest number is 16
9) Remainder 8 : Smallest number is 80

From all these series, the series that starts in the last is remainder 128 (9k+2)
So the previous number in this series must be the greatest number which we cannot form using 9 & 16 ... 128-9=119



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