Add 10 to larger numbers
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Add 10 to larger numbers: skill guide
| Objective | Learners will be able to add 10 to a two-digit number and see on ten strips that the tens digit goes up by 1 while the ones digit stays the same. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.NBT.C.5 |
| Difficulty | Developing · Mixed |
| Representation | Ten strip, Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners will be able to add 10 to a two-digit number and see on ten strips that the tens digit goes up by 1 while the ones digit stays the same.
What this practice covers
Each problem shows ten strips and an equation such as 34 + 10 or 10 + 34. The dots for the two numbers appear in two colors. Together they fill one strip for each ten in the sum, with the ones in the last strip. The learner finds the total and taps it from five choices. The two-digit number is from 21 to 89 and never ends in 0, so sums run from 31 to 99. The 10 comes first in some problems and second in others.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.1.NBT.C.5 — Given a two-digit number, mentally find 10 more or 10 less.
Who it’s for
This practice is for Grade 1 learners who can read two-digit numbers as tens and ones and are learning to add 10 in one step. It also suits older learners who still count on 10 by ones.
What to know first
- Learners should count reliably, read two-digit numerals, and understand addition as joining parts. Each problem shows the sum on ten strips.
Difficulty and scaffolding
Developing · Mixed stage
Problem representations
- Ten strip
- Numerical equation
Three worked examples
- For 34 + 10, the strips show 34 dots in one color and 10 in another. Together they fill four strips with 4 dots in the next, so the sum is 44.
- For 10 + 57, one more ten turns 5 tens into 6 tens. The 7 ones stay the same, so the sum is 67.
- For 89 + 10, 8 tens become 9 tens and the 9 ones stay, so the sum is 99.
Likely misconceptions
- Learners may count every dot from one, or count on 10 by ones and end one off, choosing 43 or 45 for 34 + 10. Show that the sum has one more full strip than the first number, so the tens digit goes up by 1 and the ones digit stays the same.
Hints and explanations
- For 34 + 10, the strips show 34 dots in one color and 10 in another. Together they fill four strips with 4 dots in the next, so the sum is 44.
- For 10 + 57, one more ten turns 5 tens into 6 tens. The 7 ones stay the same, so the sum is 67.
- For 89 + 10, 8 tens become 9 tens and the 9 ones stay, so the sum is 99.
What to practice next
Next, Large numerical sums with 10 asks for the same kind of sums with numerals only and no ten strips.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Add 10 to larger numbers FAQs
What is the goal of add 10 to larger numbers?
The goal is to add 10 to a two-digit number by changing the tens. A learner should be able to say that 34 + 10 has one more ten than 34 and the same number of ones.
Should this practice be timed?
No timer is required. First build accurate, understandable strategies. Speed usually improves as learners notice that adding 10 changes only the tens digit.
What should a learner do after a mistake?
After a wrong answer, the learner gets a second try. Count the full strips by tens, then the dots in the last strip, and compare the sum with the first number. A short explanation helps more than a quick second guess.
How many problems should be completed at once?
A Quick check has 5 problems and a Practice session has 15. A learner may pause when attention drops. A short, successful session with clear reasoning is more useful than rushing through a longer one.