Question

Momentum= mass x velocity
1507.8 x 8 = 12,506

Answer 1

$1,507.8 \cdot 8 =12,062.4 \neq 12,506$

Answer 2

You've presented two statements in your "question".
One is true and the other is false.

1).  Momentum = mass x velocity
The statement is true.

2).  1507.8 x 8 = 12,506
The statement is false.
1507.8 x 8 = 12,062.4