standard_description: Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
- The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
- 10 can be thought of as a bundle of ten ones — called a “ten.”
problem_activity: Complete the following chart:
| **           Standard Form          ** | **           Word Form          ** |                          **           Expanded Form          **                          |
|----------------------------------------|------------------------------------|------------------------------------------------------------------------------------------|
|                                        |                                    | $$(4\times1)+\left(6\times\frac{1}{100}\right) + \left(3\times{\frac{1}{1,000}}\right)$$ |
|                                        |      thirty-five thousandths       |                                                                                          |
|                 42.905                 |                                    |                                                                                          |


aligns: no