1.NBT.6

=Number and Operations in Base Ten=

1.NBT.6 - subtract multiples of 10 in the range 10 - 90 from multiples of 10 in the range of 10 - 90 (positive or 0 differences) using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between the addition and subtraction; relate the strategy to a written method and explain the reasoning used.
 * Use place value understanding and properties of operations to add and subtract**