The whole numbers are to the left of the decimal point ... the digits need to move is by looking at the zeros in 10, 100 and 1000. There are 3 zeros in 1000, so you can move the digits 3 places ...

Place value is really important when building up numbers. The order the digits are written in a number determine its value. A number can be made of more than one digit. We use place value headings ...