To multiply decimals by 10, 100, and 1000, use place value labels. Write the digits of the decimal using place value labels. Start with the first non-zero digit. To multiply by 10 move each digit one ...

19 is only 1 away from 20, so you prefer to start by multiplying 20 times 5, which equals 100. Then we need to take away a squadron of 5, because there are actually only 19 squadrons, not 20. 100 take ...