100 x 10 = 1000
100 times 10 is 1000. Multiplying by ten shifts the digits one place left, so the hundred picks up a single zero. Written as powers of ten, the exponents add: two plus one is three.
100 × 10 = 1,000
Adding 100 to itself 10 times gives the same answer.
One zero, not two
Multiplying by 10 moves the digits one place left, so 100 becomes 1000. As powers of ten it is ten squared times ten, which is ten cubed, and the exponents adding to three is the same fact as the answer carrying three zeros. The neighbour worth knowing is 100 x 100, which carries four zeros and is ten times bigger at 10000.
1000 is what a kilo means
Every kilo in the metric system is this number. 1000 grams is a kilogram, 1000 metres is a kilometre, 1000 watts is a kilowatt, 1000 millilitres is a litre. That is why so many unit conversions are just a decimal point sliding three places instead of real arithmetic.
Checks on 1000
- Halve it twice and it stays whole: 500, then 250.
- Its prime factors are 8 x 125, that is three twos and three fives.
- It is a cube as well: 10 x 10 x 10.
- It is not prime. It has 16 divisors, from 1 up to 1000 itself.
Do not confuse it with
100 + 10 is 110, which is addition. 1000 x 10 is 10000, one shift further along. 1000 x 1000 is 1000000, the same idea taken to a million. The calculator above takes any pair, and the whole set is at multiplication answers.