Mental Math Within 100 Worksheets for Grade 2

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Browse all 12 printable worksheets below — click any card to open the full page.

Easy

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Sort the Words

Sort each word or number into the correct category box.

Part B: Fill in the Blank

Write the missing word or number on each line.

1. 42 + 35: tens part is 40 + 30 =  

2. 42 + 35: ones part is 2 + 5 =  

3. Put the tens and ones back together: 70 + 7 =  

4. Break apart 53 + 24. The tens part is 50 + 20 =  

5. Break apart 61 + 28. The full sum is  

Part C: True or False?

Read each statement. Circle True or False.

1. 44 + 32 can be split into 40 + 30 and 4 + 2.

T F

2. To add 50 + 40, you need to break apart any ones.

T F

3. When you break apart 26 + 13, the ones add to 9.

T F

4. Breaking apart numbers makes mental math harder.

T F

Mental Math Within 100

Easy

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Sort the Words

Sort each word or number into the correct category box.

Part B: Fill in the Blank

Write the missing word or number on each line.

1. Start at 56 and count on 20 by tens: 56, 66,  

2. Start at 34 and count on by tens three times: 34, 44, 54,  

3. 47 + 30 by counting on tens equals  

4. Count on by ones: 82 + 3 =  

5. 20 + 63 counted as tens then ones is  

Part C: True or False?

Read each statement. Circle True or False.

1. Counting on by tens means the ones digit stays the same.

T F

2. 56 + 20 gives the same answer as 56, 66, 76.

T F

3. To add 45 + 4 quickly, you should count by tens.

T F

4. Counting on is slower than using fingers for every number.

T F

Mental Math Within 100

Easy

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Sort the Words

Sort each word or number into the correct category box.

Part B: Fill in the Blank

Write the missing word or number on each line.

1. Use a number bond of 10 to finish: 8 +  

2. To add 37 + 3 quickly, notice that 7 + 3 makes 10. The answer is  

3. 52 + 8 uses 2 + 8 = 10, so the sum lands on  

4. 6 +  

5. 74 + 6 equals  

Part C: True or False?

Read each statement. Circle True or False.

1. 7 and 3 are number bond partners because together they make 10.

T F

2. Making tens helps you solve problems like 48 + 2 quickly.

T F

3. 5 and 6 are partners that make 10.

T F

4. Knowing number bonds of 10 has nothing to do with adding two-digit numbers.

T F

Mental Math Within 100

Easy

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Sort the Words

Sort each word or number into the correct category box.

Part B: Fill in the Blank

Write the missing word or number on each line.

1. 54 + 10 =  

2. 27 + 20 =  

3. 63 + 30 =  

4. Adding 10 to 41 changes only the tens digit, giving  

5. 35 + 40 =  

Part C: True or False?

Read each statement. Circle True or False.

1. When you add 10 to any number, only the tens digit changes.

T F

2. 27 + 20 equals 29 because you just add the 2.

T F

3. To add 35 + 40 mentally, you can count four tens up from 35.

T F

4. Adding a number that ends in zero is harder than adding ones.

T F

Mental Math Within 100

Medium

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Fill in the Blank

Write the missing word or number on each line.

1. Double 25 means 25 + 25 =  

2. Double 30 is  

3. A near-double like 25 + 26 equals (25 + 25) + 1 =  

4. 24 + 25 uses the double of 24, which is 48, plus 1. The sum is  

5. Double 15 is  

6. 40 + 41 = double 40 + 1 =  

7. Double 35 = 35 + 35 =  

8. Near-double 19 + 20 is (double 19) + 1 = 38 + 1 =  

9. Double 45 is  

Part B: Matching

Match each item on the left to the correct answer on the right.

1. Match each item to its correct answer.

Double 20

→

40

Double 22

→

44

23 + 24

→

47

30 + 31

→

61

Mental Math Within 100

Medium

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Fill in the Blank

Write the missing word or number on each line.

1. 48 + 19 can become 48 + 20, then subtract  

2. 48 + 20 = 68, then 68 - 1 =  

3. 35 + 29 becomes 35 + 30 - 1 =  

4. 44 + 39 becomes 44 + 40 - 1 =  

5. 27 + 18 becomes 27 + 20 - 2 =  

6. If you change 49 + 32 into 50 + 32 -  

7. Using compensation, 25 + 48 = 25 + 50 - 2 =  

8. To add 63 + 19 use 63 + 20 - 1 =  

9. Compensation means you change one number to make it  

Part B: Matching

Match each item on the left to the correct answer on the right.

1. Match each item to its correct answer.

46 + 19

→

46 + 20 - 1

27 + 29

→

27 + 30 - 1

52 + 38

→

52 + 40 - 2

35 + 48

→

35 + 50 - 2

Mental Math Within 100

Medium

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Fill in the Blank

Write the missing word or number on each line.

1. 35 + 8: first add 5 to reach 40, then 3 more. Sum is  

2. 28 + 7 = 28 + 2 + 5, which equals  

3. 47 + 6 = 47 + 3 + 3 =  

4. To solve 69 + 5, first add  

5. 69 + 5 = 69 + 1 + 4 =  

6. 56 + 9 = 56 + 4 + 5, which gives  

7. 72 + 8 uses 8 =  

8. 48 + 7 = 48 + 2 +  

9. 29 + 6 = 29 + 1 + 5 =  

Part B: Matching

Match each item on the left to the correct answer on the right.

1. Match each item to its correct answer.

38 + 5

→

38 + 2 + 3

46 + 7

→

46 + 4 + 3

59 + 4

→

59 + 1 + 3

27 + 6

→

27 + 3 + 3

Mental Math Within 100

Medium

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Fill in the Blank

Write the missing word or number on each line.

1. 25 + 40 =  

2. 35 + 40 =  

3. 45 + 40 =  

4. The ones digit stays the same in these patterns. It is always  

5. 16 + 20 =  

6. 26 + 20 =  

7. 36 + 20 =  

8. 50 + 30 =  

9. 60 + 30 =  

Part B: Matching

Match each item on the left to the correct answer on the right.

1. Match each item to its correct answer.

22 + 30

→

52

32 + 30

→

62

42 + 30

→

72

52 + 30

→

82

Mental Math Within 100

Hard

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Multiple Choice

Circle the best answer for each question.

1. Use parts to solve 65 - 22. First do 65 - 20, then subtract 2. What is the answer?

2. Which is the quickest mental strategy for 80 - 39?

3. Count back from 78 by tens three times. What number do you land on?

4. Which split is best for mentally finding 94 - 37?

Part B: Fill in the Blank

Write the correct answer on each line.

1. 70 - 25 by parts is (70 - 20) - 5 =  

2. Count back by tens: 83, 73, 63, 53. So 83 - 30 =  

3. Use compensation: 62 - 19 = 62 - 20 + 1 =  

4. 90 - 48 using compensation is 90 - 50 + 2 =  

5. 56 - 24 split into parts is 56 - 20 - 4 =  

Mental Math Within 100

Hard

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Multiple Choice

Circle the best answer for each question.

1. A store had 48 apples and sold 19. Which is the best mental step?

2. Leo has 34 stickers. He gets 30 more. How many stickers does he have now?

3. What is 25 + 26 using a near-double?

4. A bus has 72 seats. 28 people get off. Which step is best?

Part B: Fill in the Blank

Write the correct answer on each line.

1. A book has 45 pages. Mia reads 20. Pages left: 45 - 20 =  

2. Ben had 29 marbles and found 30 more. Using a near-double, the total is  

3. A bag has 38 candies. You add 19 more. Using compensation, the total is  

4. A pond has 60 ducks. 25 fly away. Remaining:  

5. Tia scored 27 and 27 points on two quizzes. Using doubles her total is  

Mental Math Within 100

Hard

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Multiple Choice

Circle the best answer for each question.

1. Which strategy works best for 34 + 29?

2. Which is the best break-apart step for 46 + 27?

3. Which approach is easiest for 58 + 19?

4. Which strategy is best for 25 + 38?

Part B: Fill in the Blank

Write the correct answer on each line.

1. 34 + 29 using compensation is 34 + 30 - 1 =  

2. 46 + 27 by break-apart: 40 + 20 = 60 and 6 + 7 = 13, sum is  

3. 58 + 19 by compensation is 58 + 20 - 1 =  

4. 25 + 38 using compensation is 25 + 40 - 2 =  

5. 62 + 25 by break-apart: 60 + 20 = 80 and 2 + 5 = 7. Sum is  

Mental Math Within 100

Hard

Mental Math Within 100

Name:

Date:

Grade: Grade 2

Part A: Multiple Choice

Circle the best answer for each question.

1. What is the best mental step for 52 - 28?

2. To solve 63 - 27 by counting up, what is the first friendly jump?

3. Which strategy works best for 81 - 49?

4. Which is the best break-apart for 74 - 36?

Part B: Fill in the Blank

Write the correct answer on each line.

1. A box has 52 crayons. 28 are used. Remaining crayons: 52 - 30 + 2 =  

2. A bag has 63 beads and 27 fall out. Count up 3 to 30, then 30 to 60, then 3 to 63. Beads lost:  

3. There are 81 chairs and 49 are in use. Empty chairs: 81 - 50 + 1 =  

4. A shelf has 74 books. 36 are loaned out. Remaining: 74 - 30 - 6 =  

5. A pond had 90 frogs and 47 hopped away. Remaining: 90 - 50 + 3 =  

Mental Math Within 100

What's Included in This Download

What You'll Learn

These mental math within 100 worksheets help grade 2 students develop essential math skills through engaging activities.

Learning Objectives

• Mental Math Within 100: Apply mental math strategies for addition and subtraction within 100
• Mental Math Within 100: Break apart tens and ones to compute fluently
• Mental Math Within 100: Use count-on, doubles, and compensation strategies
• Mental Math Within 100: Solve word problems mentally

Skills Covered

How to Use These Worksheets

1. Download & Print: Click the download button to get the PDF. Print on standard 8.5" x 11" paper.
2. Start Simple: Begin with easier pages before moving to more challenging activities.
3. Daily Practice: Dedicate 10-15 minutes each day for consistent learning.
4. Use Manipulatives: Pair worksheets with physical objects like blocks or counters.
5. Provide Encouragement: Celebrate progress and effort to build confidence.
6. Check Progress: Use the included answer key to review work together.

Common Mistakes to Watch For

• Forgetting to subtract back the extra amount after rounding up with compensation, such as writing 48 + 19 = 68 instead of 67.
• Counting on by ones when the number clearly calls for jumps of ten, which is slow and leads to errors like 56 + 20 = 60.
• Adding the tens and ones separately but forgetting to combine them, so 42 + 35 becomes just 70 or just 7 instead of 77.

Frequently Asked Questions

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