Just want to know what is mean when we write 10!+20, I man how do u simply this?
Thanks
10!+20
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10! + 20 = (10)(9)(8)..(3)(2)(1) + 20[email protected] wrote:Just want to know what is mean when we write 10!+20, I man how do u simply this?
Thanks
The GMAT would never require you to actually evaluate this (too many tedious calculations)
Cheers,
Brent
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Thanks Brent, the question is how many numbers between 10! and 10!+20 are divisible by 3.
Brent@GMATPrepNow wrote:10! + 20 = (10)(9)(8)..(3)(2)(1) + 20[email protected] wrote:Just want to know what is mean when we write 10!+20, I man how do u simply this?
Thanks
The GMAT would never require you to actually evaluate this (too many tedious calculations)
Cheers,
Brent
GMAT/MBA Expert
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NOTE: I reworded the question to avoid ambiguity.[email protected] wrote:How many numbers from 10! to 10!+20 inclusive, are divisible by 3?
There's a nice rule that says: If M is divisible by k, and N is divisible by k, then (M + N) is divisible by k.
First, since 10! = (10)(9)(8)..(3)(2)(1), we know that 10! is divisible by 3.
So, by the above rule, we know that 10! + 3 is divisible by 3
And 10! + 6 is divisible by 3
10! + 9 is divisible by 3
10! + 12 is divisible by 3
10! + 15 is divisible by 3
10! + 18 is divisible by 3
So, there are 7 integers from 10! to 10! + 20 inclusive that are divisible by 3.
Cheers,
Brent