Large numerical sums with 10
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Large numerical sums with 10: skill guide
| Objective | Learners will be able to add 10 to a two-digit number from the numerals alone by raising the tens digit by 1. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.NBT.C.4 |
| Difficulty | Developing · Abstract |
| Representation | Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners will be able to add 10 to a two-digit number from the numerals alone by raising the tens digit by 1.
What this practice covers
Each problem shows an equation such as 45 + 10 or 10 + 45, with a blank for the total. There is no picture. The learner finds the sum 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.4 — Add within 100, including adding a two-digit number and a multiple of 10.
Who it’s for
This practice is for Grade 1 learners who read two-digit numbers as tens and ones and are ready to add 10 from the numerals alone. 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. Problems show numerals only.
Difficulty and scaffolding
Developing · Abstract stage
Problem representations
- Numerical equation
Three worked examples
- For 45 + 10, the tens digit goes from 4 to 5 and the ones digit stays 5, so the sum is 55.
- For 10 + 72, seven tens and one more ten make 8 tens. The 2 ones stay, so the sum is 82.
- For 86 + 10, eight tens become 9 tens and the 6 ones stay, so the sum is 96.
Likely misconceptions
- Learners may count on 10 by ones and end one off, choosing 54 or 56 for 45 + 10. Point out that adding 10 raises the tens digit by 1 and leaves the ones digit the same.
Hints and explanations
- For 45 + 10, the tens digit goes from 4 to 5 and the ones digit stays 5, so the sum is 55.
- For 10 + 72, seven tens and one more ten make 8 tens. The 2 ones stay, so the sum is 82.
- For 86 + 10, eight tens become 9 tens and the 6 ones stay, so the sum is 96.
What to practice next
Next, Complete addition patterns shows five numbers that each go up by 10, with one number missing for the learner to fill in.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Large numerical sums with 10 FAQs
What is the goal of large numerical sums with 10?
The goal is to add 10 to any two-digit number by changing the tens digit. A learner should be able to explain why the ones digit stays the same.
Should this practice be timed?
No timer is required. First build accurate, understandable strategies. Speed usually improves as learners trust 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. Read the first number as tens and ones, add one ten, and say the new 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.