standard_description: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, 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. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
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