Number & Operations in Base Ten

Extend the counting sequence.

1.NBT.1 Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.

Count to 50

Count to 50

Count to 100

Count to 100

Count to 120

Count to 120

Understand place value.

1.NBT.2 Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:

Count groups of 10

Count Groups of 10

Multiples of 10

Multiples of 10

Numbers up to 20

Numbers up to 20

Numbers up to 50

Numbers up to 50

Numbers up to 100

Numbers up to 100

1.NBT.2.a 10 can be thought of as a bundle of ten ones — called a "ten."

Count groups of 10

Count Groups of 10

1.NBT.2.b The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.

Numbers up to 20

Numbers up to 20

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).

Multiples of 10

Multiples of 10

1.NBT.3 Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.

Compare numbers

Compare Numbers

Order numbers up to 20

Order Numbers up to 20

Use place value understanding and properties of operations to add and subtract.

1.NBT.4 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.

Add multiples of 10

Add Multiples of 10

Add tens to a 2 digit number

Add Tens to a 2 Digit Number

Add ones to a 2 digit number

Add Ones to a 2 Digit Number

1.NBT.5 Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

1.NBT.6 Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.

Subtract multiples of 10

Subtract Multiples of 10