500 x 1000 = 500000
500 times 1000 is 500000, or half a million. Because 500 is half of 1000, the answer is exactly half of 1000 x 1000, which makes it easy to check in your head.
500 × 1,000 = 500,000
Adding 500 to itself 1,000 times gives the same answer.
The fastest way to do it
Multiply 5 by 1, then count zeros. 500 carries two and 1000 carries three, so the answer carries five: 500000. The halving check confirms it from a second direction, since 1000 x 1000 is 1000000 and 500 is half of 1000.
Where half a million turns up
Any per-unit figure of 500 scaled to a thousand units lands on 500000. 500 grams a thousand times over is 500000 grams, which is 500 kilograms. 500 meters a thousand times is 500 kilometers. The digits never move; only the unit name does.
The calculation next door
A single zero separates this from its neighbors. 500 x 100 is 50000, ten times smaller, and 2000 x 1000 is 2000000, four times larger. If an answer looks wrong by a factor of ten, a miscounted zero is almost always the cause.
About 500000
500000 is a 5 with five zeros after it. Its only prime factors are 2 and 5, which is precisely why it reads as a round number in base ten: ten is 2 x 5, so numbers built from nothing but twos and fives end in zeros. Compare 200 x 1000 = 200000.