2.NBT.A.1.a
100 can be thought of as a bundle of ten tens — called a "hundred."
2.NBT.A.1.b
The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).
2.NBT.A.3
Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.