10000 x 100 = 1000000
10000 times 100 is 1000000, or one million. Both numbers are round powers of ten, so the shortcut is to count zeros: four from 10000, two from 100, six on the answer.
10,000 × 100 = 1,000,000
Adding 10,000 to itself 100 times gives the same answer.
How 10000 x 100 reaches 1000000
10000 x 100 = 1000000. Both numbers here are round powers of ten. 10000 is ten to the fourth power and 100 is ten to the second. Multiplying powers of ten means adding those exponents, so four plus two gives six: ten to the sixth power, which is one million.
The zero count
The quick version needs no exponents at all. Write the 1, then carry over every zero from both numbers.
- 10000 brings four zeros.
- 100 brings two zeros.
- A 1 followed by six zeros is 1000000.
Order changes nothing, so 100 x 10000 gives the same 1000000.
Other routes to one million
1000000 is a square number. 1000 x 1000 lands on it too, because 1000 multiplied by itself is 1000000. Whenever a product ends in six zeros, the two numbers you started with held six zeros between them.
The mistake to watch for
The near neighbour is 10000 x 1000, which is 10000000, ten million. One extra zero in the second number lifts the answer by a whole factor of ten. Count the zeros before you trust a million. The rest are collected on the multiplication answers index.