standard_description: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
problem_activity: Problem 1
Use the fact that 221 ÷ 17 = 13 to solve the following.
22.1 ÷ 17
2.21 ÷ 17
221 ÷ 1.7
221 ÷ 0.17
22.1 ÷ 1.7
2.21 ÷ 0.17
How did you determine where the decimal point would be in the quotients in Part (a) above? Why does that make sense?
Problem 2
Solve. Show or explain your work.
51 ÷ 6
45.2 ÷ 5
3.7 ÷ 20
14.04 ÷ 52
0.9 ÷ 0.25
27.54 ÷ 3.4


aligns: no