Component
1.NBT.2.c: 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).
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- Number and Operations in Base Ten
- Understand place value.
- Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
- 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).