standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
problem_activity: Problem 1
Solve. Show or explain your work.
a.
$${91\div20}$$
b.
$${368\div50}$$
Problem 2
Use multiplication to check your answers to both problems in Problem 1.


aligns: no