100000 x 1000 = 100000000
100000 times 1000 is 100000000, one hundred million. Both sides are powers of ten, so nothing needs multiplying: five zeros plus three zeros makes eight behind the 1.
100,000 × 1,000 = 100,000,000
Adding 100,000 to itself 1,000 times gives the same answer.
The working
Both numbers are powers of ten, so the only work is counting. 100000 carries five zeros, 1000 carries three, and five plus three is eight. The answer is a 1 followed by eight zeros: 100000000.
The same answer from a different pair
Any two powers of ten whose zero counts add to eight land here. 10000 x 10000 does it with four and four, 1000000 x 100 with six and two, 10000000 x 10 with seven and one. Of those, 10000 x 10000 = 100000000 is the one most people search for, because it makes 100000000 the square of 10000.
The near misses that land on ten million
Drop a single zero from either side and the answer drops by a factor of ten. 100000 x 100 is 10000000 and 10000 x 1000 is also 10000000 – ten million, not a hundred million. Counting the zeros in both inputs before writing the answer is the whole check.
Reading the number out
100000000 is one hundred million in English. In the Indian grouping it is 10 crore, since one crore is 10000000. As a power it is ten to the eighth, and its only prime factors are 2 and 5, each appearing eight times.
The ladder
| Calculation | Answer |
|---|---|
| 1000 x 1000 | 1000000 |
| 10000 x 1000 | 10000000 |
| 100000 x 1000 | 100000000 |
Every pair on the site is listed in multiplication answers.