Solve 20*19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1

$$20 \times 19 \times 18 \times 17 \times 16 \times 15 \times 14 \times 13 \times 12 \times 11 \times 10 \times 9 \times 8 \times 7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1$$

Evaluate

$$2432902008176640000$$

Solution Steps

Multiply 20 and 19 to get 380.

$$380\times 18\times 17\times 16\times 15\times 14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 380 and 18 to get 6840.

$$6840\times 17\times 16\times 15\times 14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 6840 and 17 to get 116280.

$$116280\times 16\times 15\times 14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 116280 and 16 to get 1860480.

$$1860480\times 15\times 14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 1860480 and 15 to get 27907200.

$$27907200\times 14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 27907200 and 14 to get 390700800.

$$390700800\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 390700800 and 13 to get 5079110400.

$$5079110400\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 5079110400 and 12 to get 60949324800.

$$60949324800\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 60949324800 and 11 to get 670442572800.

$$670442572800\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 670442572800 and 10 to get 6704425728000.

$$6704425728000\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 6704425728000 and 9 to get 60339831552000.

$$60339831552000\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 60339831552000 and 8 to get 482718652416000.

$$482718652416000\times 7\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 482718652416000 and 7 to get 3379030566912000.

$$3379030566912000\times 6\times 5\times 4\times 3\times 2\times 1$$

Multiply 3379030566912000 and 6 to get 20274183401472000.

$$20274183401472000\times 5\times 4\times 3\times 2\times 1$$

Multiply 20274183401472000 and 5 to get 101370917007360000.

$$101370917007360000\times 4\times 3\times 2\times 1$$

Multiply 101370917007360000 and 4 to get 405483668029440000.

$$405483668029440000\times 3\times 2\times 1$$

Multiply 405483668029440000 and 3 to get 1216451004088320000.

$$1216451004088320000\times 2\times 1$$

Multiply 1216451004088320000 and 2 to get 2432902008176640000.

$$2432902008176640000\times 1$$

Multiply 2432902008176640000 and 1 to get 2432902008176640000.

$$2432902008176640000$$

Factor

$$2^{18}\times 3^{8}\times 5^{4}\times 7^{2}\times 11\times 13\times 17\times 19$$