In this Grade 2 worksheet, second graders practice counting on by tens to add within 100. Sorting items separate problems that jump by tens from those that jump by ones, and fill-ins guide students step by step through mental count-on sequences. True or false questions reinforce that counting on by tens keeps the ones digit the same and is faster than counting by ones, supporting flexible mental math strategies.
Style:
Mental Math Within 100
Part A: Sort the Words
Sort each word or number into the correct category box.
56 + 2043 + 330 + 2771 + 440 + 2562 + 2
Count on by tens
Count on by ones
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, 76.
2. Start at 34 and count on by tens three times: 34, 44, 54, 64.
3. 47 + 30 by counting on tens equals 77.
4. Count on by ones: 82 + 3 = 85.
5. 20 + 63 counted as tens then ones is 83.
Part C: True or False?
Read each statement. Circle True or False.
1. Counting on by tens means the ones digit stays the same.
True False
2. 56 + 20 gives the same answer as 56, 66, 76.
True False
3. To add 45 + 4 quickly, you should count by tens.
True False
4. Counting on is slower than using fingers for every number.
True False
Mental Math Within 100
★ Part A: Sort the Words
Sort each word or number into the correct category box.
56 + 2043 + 330 + 2771 + 440 + 2562 + 2
Count on by tens
Count on by ones
★ 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, 76.
2) Start at 34 and count on by tens three times: 34, 44, 54, 64.
3) 47 + 30 by counting on tens equals 77.
4) Count on by ones: 82 + 3 = 85.
5) 20 + 63 counted as tens then ones is 83.
★ Part C: True or False?
Read each statement. Circle True or False.
1) Counting on by tens means the ones digit stays the same.
True
False
2) 56 + 20 gives the same answer as 56, 66, 76.
True
False
3) To add 45 + 4 quickly, you should count by tens.
True
False
4) Counting on is slower than using fingers for every number.
True
False
Ready to Practice?
Complete each section carefully.
10 Questions
15-20 minutes
Auto-graded
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