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標題:

1*2*3*4*5*..................................999*1000=?

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發問:

1*2*3*4*5*..................................999*1000=?

最佳解答:

1*2*3*4*5*..................................999*1000 =(1+1000)x1000/2[頭+尾x項數/2] =1001*1000/2 =1001000/2 =500500

其他解答:

That person is WRONG la, (1+1000) x 1000/2 only applies on 1 + 2 + 3 + ..... +999 + 1000 now it's multiplcation, notes that 999*1000 already =999000, so it's impossible for the answer to be 555000 1 x 2 x 3 ... x 1000 = 1000! (factorial) use the calculation, look for the "!" sign, usually it's "n! " just type 1000! , u will get 4.0238 x 10 ^2567 it's a BIG number!!!5AEEC82B53E1B405