Remembering how to count by $10$10's can help us when we need to multiply by $10$10.
Complete the pattern by adding $10$10 each time.
$20$20, $\editable{}$, $40$40, $\editable{}$, $\editable{}$
Let's look at how to multiply numbers by 10.
Another word that we can use to describe the ones place is 'units'.
$10\times4$10×4
A quick way to multiply any whole number by $10$10 is to add a $0$0 at the end.
That moves all our numbers up one place in the place value table, with the $0$0 as a place holder in the ones column.
However, this rule is ONLY true for whole numbers, so you have to be careful once fractions or decimals are involved.