1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16x17x18x19x20x21x22x23x24x25x26x27x28x29x30x31x32x33x34x35x36x37x38x39x40x41x42x43x44x45x46x47x48x49x50x51x52x53x4x55x56x57x58x59x60x61x62x63x64x65x66x67x68x69x70x71x72x73x74x75x76x77x78x79x80x81x82x83x84x85x86x87x88x89x90x91x92x93x94x95x96x97x98x99x100
=可以用乘法交换率
=(1x2x3x4x5x6x7x8x9x10)x(11x12x13x14x15x16x17x18x19x20)x(21x22x23x24x25x26x27x28x29x30)x(31x32x33x34x35x36x37x38x39x40)x(41x42x43x44x45x46x47x48x49x50)x(51x52x53x4x55x56x57x58x59x60)x(61x62x63x64x65x66x67x68x69x70)x(71x72x73x74x75x76x77x78x79x80)(81x82x83x84x85x86x87x88x89x90)x(90x91x92x93x94x95x96x97x98x99x100)
数太大了 100!=9.3326215443944152681699238856267e+157
30414093201713378043612608166064768844377641568960512000000000000 一共有24个零 一点错都不会有的
