Virginia SOL Math / Grade 2 / Computation & Estimation
Add & Subtract Within 100
What you'll learn
- Recall addition and subtraction facts within 20
- Add and subtract two-digit numbers with and without regrouping
- Solve single-step word problems within 100
Words to know
- Sum —
- the answer to an addition problem
- Difference —
- the answer to a subtraction problem
- Regroup —
- trade 10 ones for 1 ten, or 1 ten for 10 ones
- Fact family —
- related addition and subtraction facts, like 3 + 4 and 7 - 4
Why it matters Adding and subtracting helps us total things up and find how many are left, such as counting toys or sharing snacks.
Worked examples
Model ItI do
Add 34 + 28.
Add the ones: 4 + 8 = 12. That is 1 ten and 2 ones, so regroup. Add the tens: 3 + 2 + 1 = 6 tens. The sum is 62.
Try It TogetherWe do
Find 52 - 17.
We cannot take 7 ones from 2 ones, so regroup 1 ten into 10 ones, making 12 ones. Then 12 - 7 = 5 ones, and 4 - 1 = 3 tens. The difference is 35.
Now YouYou do
A jar had 45 marbles. You added 26 more. How many marbles now?
Decide the operation, then add. Check your answer in the back of this chapter.
Practice
Mastered 0 of 11
Warm-up
Ease in with the basics.
1.Find 5 + 4.
2.Find 10 - 3.
3.Find 20 + 30.
On Level
The core Quick Check from the book.
1.Find 8 + 7.
2.Find 46 + 23.
3.Find 70 - 25.
4.There are 60 stickers. You give away 18. How many are left?
5.Write the missing number: 9 + ___ = 15.
Challenge
Stretch your thinking.
1.Find 47 + 38.
2.Find 83 - 46.
3.A class had 92 stickers. They used 57. How many stickers are left?