# Number & Operations in Base Ten - 2nd Grade Common Core Math

## 2.NBT.1

Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones; e.g., 706 equals 7 hundreds, 0 tens, and 6 ones. Understand the following as special cases:

Represent 3 Digit Numbers

Understanding Place Value

Expanded Forms

## 2.NBT.1.a

100 can be thought of as a bundle of ten tens — called a "hundred."

## 2.NBT.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.2

Count within 1000; skip-count by 5s, 10s, and 100s.

Count by 2's

Count by 5's

Count by 10's

Count by 100's

## 2.NBT.3

Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.

Understanding Place Value

Expanded Forms

## 2.NBT.4

Compare two three-digit numbers based on meanings of the hundreds, tens, and ones digits, using >, =, and < symbols to record the results of comparisons.

Compare Numbers upto 1000

Order Numbers upto 1000

## 2.NBT.5

Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

2 Digit + 1 Digit

2 Digit + 2 Digit

2 Digit + 1 Digit with Regrouping

2 Digit + 2 Digit with Regrouping

Subtract Tens from a 2 Digit Number

2 Digit - 1 Digit

2 Digit - 2 Digit

2 Digit - 1 Digit with Regrouping

2 Digit - 2 Digit with Regrouping

Subtraction Word Problems within 100

## 2.NBT.6

Add up to four two-digit numbers using strategies based on placevalue and properties of operations.

## 2.NBT.7

Add and subtract within 1000, 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. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.

3 Digit + 1 Digit

3 Digit + 2 Digit

3 Digit + 3 Digit

Add by Composing Tens and Hundreds

Subtract Multiples of 100

3 Digit - 1 Digit

3 Digit - 2 Digit

3 Digit - 3 Digit

Subtract by Breaking up Tens

Subtract by Breaking up Hundreds

Subtract by Breaking up Tens and Hundreds

Subtraction Word Problems within 1000

## 2.NBT.8

Mentally add 10 or 100 to a given number 100—900, and mentally subtract 10 or 100 from a given number 100—900.

Add 10 or 100 to a 3 Digit Number

Subtract 10 or 100

## 2.NBT.9

Explain why addition and subtraction strategies work, using place value and the properties of operations.