20 x 100 = 2000
20 times 100 is 2000, and 100 times 20 gives the same answer. Multiplying by 100 moves every digit two places to the left, which on a whole number looks like writing two more zeros.
20 × 100 = 2,000
Adding 20 to itself 100 times gives the same answer.
Shift two places, do not add two zeros
Multiplying by 100 shifts each digit two places to the left. For a whole number like 20 that looks the same as writing two extra zeros, so 20 becomes 2000. Learn it as a shift anyway, because the zero version falls apart on decimals: 0.2 x 100 is 20, not 0.200. Order makes no difference either, so the search for 100 x 20 lands on this same 2000.
The percent trap
Most of the wrong answers here come from reading times as of.
- 20 x 100 = 2000
- 20 percent of 100 = 20
- 20 out of 100 = 0.2 as a decimal
The 100 in a percentage divides; the 100 in this calculation multiplies. Going the other way, multiplying a decimal by 100 is exactly the step that turns 0.2 into the figure 20.
What 2000 is a quantity of
2000 is two thousand: 2 kilograms written out in grams, 2 kilometres in metres, 2 litres in millilitres. As a stretch of time it is 33 minutes and 20 seconds. Split into prime factors it is 16 x 125, so it divides cleanly by 8, 16, 25, 80 and 125, and it has 20 whole divisors in all.
The pair next door
An easy slip is one digit up on the left: 200 x 100 is 20000, ten times this answer. One step down, 100 x 10 is 1000, half of it. Everything else is listed at multiplication answers.