Use what you know about addition to find:
$9+2=\editable{}$9+2=
We know that:
$9+2=11$9+2=11.
Use this to find:
$19+2=\editable{}$19+2=
We know that
$9+2=11$9+2=11.
Use this to find:
$9+12=\editable{}$9+12=
$19+2=21$19+2=21. Use this to find:
$2+19=21$2+19=21. Use this to find:
Fill in the boxes with the missing numbers.
Know how many ones, tens, and hundreds are in whole numbers to at least 1000.
Generalise that whole numbers can be partitioned in many ways