Grade 1
Domain Number and Operations in Base Ten
Cluster Use place value understanding and properties of operations to add and subtract.
Standard Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

1.NBT.C.5. Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.