standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Solve. Show or explain your work.
a.
$$0.35 \times 0.4$$
b.
$$2.02 \times 4.2 $$


aligns: no