1.4 x 1000 = 1400
1.4 times 1000 is 1400. Multiplying by a thousand moves the decimal point three places right, which is the same arithmetic behind every metric step: 1.4 kilograms is 1400 grams.
1.4 × 1,000 = 1,400
Three hops, not two
1.4 has a single digit after the point. Moving three places right consumes that digit and then borrows two zeros: 1.4 becomes 14, then 140, then 1400. The common slip is stopping one hop early at 140, which is what 1.4 x 100 gives, not 1.4 x 1000.
Where it shows up
Every jump between a metric unit and its milli- or kilo- neighbor is a multiplication by 1000. 1.4 kilograms is 1400 grams. 1.4 kilometers is 1400 meters. 1.4 liters is 1400 milliliters. 1.4 seconds is 1400 milliseconds. The digits stay identical and only the unit changes, which is the whole point of the metric system.
The other route to 1400
The same answer arrives from a different pair: 14 x 100 is also 1400. Dividing one number by ten while multiplying the other by ten leaves the product untouched, so 1.4 x 1000 and 14 x 100 are the same calculation shifted one step apart.