# Number & Operations in Base Ten

**Number & Operationsin Base Ten (NBT)**

Extend the counting sequence.

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.

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:

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

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).

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

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

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.

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

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.

**Number & Operations in Base Ten (NBT) 1.NBT.1**

**1.NBT.A.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.

**Watch This Video**

**Missing numbers between 0 and 120 | Counting | Early Math | Khan Academy**

**Number & Operations in Base Ten (NBT) ****1.NBT.A1**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 1.NBT.2**

**1.NBT.B.2**

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

**1.NBT.B.2a**

10 can be thought of as a bundle of ten ones called a "ten."

**1.NBT.B.2b**

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

**1.NBT.B.2c**

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).

**Watch This Video**

**Introduction to place value | Place value (tens and hundreds) | Early Math | Khan Academy**

**Number & Operations in Base Ten (NBT)**

**1.NBT.B2a**

**IXL Activities**

**Number & Operations in Base Ten (NBT)**

**1.NBT.B2b**

**IXL Activities**

**Number & Operations in Base Ten (NBT)**

**1.NBT.B2c**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 1.NBT.3**

**1.NBT.B.3**

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

**Watch This Video**

**Comparing whole numbers | Place value (tens and hundreds) | Early Math | Khan Academy**

**Khan Academy: **Practice comparing numbers using the symbols <, >, and =. All numbers in these problems are within 100.

Do these activities: **KHAN ACADEMY 1.NBT.B.3 ACTIVITY 1 - Comparing two-digit numbers 1**

**Watch This Video**

**Place value example with 42 | Place value (tens and hundreds) | Early Math | Khan Academy**

**Number & Operations in Base Ten (NBT)**

**1.NBT.B3**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 1.NBT.4**

**1.NBT.C.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.

**Watch This Video**

**Khan Academy: **Practice comparing numbers using the symbols <, >, and =. All numbers in these problems are within 100.

Do these activities: **KHAN ACADEMY 1.NBT.C.4 ACTIVITY 1 - Adding 1s or 10s - Practice solving problems like 34+1 and 34+10.**

**Watch This Video**

**Understanding place value when adding ones | Early Math | Khan Academy**

Do these activities: **KHAN ACADEMY 1.NBT.C.4 ACTIVITY 3 - Adding two-digit numbers (no regrouping)**

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**Watch This Video**

Do these activities: **KHAN ACADEMY 1.NBT.C.4 ACTIVITY 4 - Breaking apart two-digit addition problems**

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**Watch This Video**

**Adding by getting to group of 10 first | Early Math | Khan Academy**

**Number & Operations in Base Ten (NBT)**

**1.NBT.C4**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 1.NBT.5**

**1.NBT.C.5**

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

**Watch This Video**

**Adding 1 vs. adding 10 | Addition and subtraction | 1st grade | Khan Academy**

**Number & Operations in Base Ten (NBT) 2.NBT.2**

**2.NBT.A.2**

Count forward and backward within 1000; skip count by 5's, 10's, and 100's beginning at any multiple of 5.

**Khan Academy: **Count within 1000; skip-count by 5s, 10s, and 100s.

**Watch This Video**

**Number & Operations in Base Ten (NBT) ****2.NBT.A2**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 2.NBT.4**

**2.NBT.A.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.

**Watch This Video**

Do these activities: **KHAN ACADEMY 1.NBT.C.4 ACTIVITY 1 - Compare 3-digit numbers**

**Watch This Video**

**Subtracting a 1-digit number with regrouping | 2nd grade | Khan Academy**

**Number & Operations in Base Ten (NBT)**

**2.NBT.A4**

**IXL Activities**

**Number & Operations in Base Ten (NBT) 2.NBT.8**

**2.NBT.B.8**

**Mentally add or subtract 10 or 100 from any given number between 100 and 900.**

**Khan Academy: **Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.

**Watch This Video**

Skills for this standard are **coming soon** to Khan Academy.

Do these activities: **KHAN ACADEMY 2.NBT.B.8 ACTIVITIES - Coming Soon**

**Number & Operations in Base Ten (NBT) ****2.NBT.B8**

**IXL Activities**

**Number & Operations in Base Ten (NBT)**

Extend the counting sequence, understand place value, and apply place value understanding.

**Counting Games**

**Jumping Chicks **

Power your chicks by counting lily pads.

**Koala Karts **

Power your racecar by counting discs.

**Challenging Games**

**Canoe Puppies Race Game**

Add two-digit numbers correctly to win the race.

**Missing Number Addition**

Choose a target sum from (20-100) to practice.

**Missing Number Subtraction**

Choose a target difference from (20-100) to practice.