Virginia SOL Math / Grade 3 / Computation & Estimation

3.CE.1

Add & Subtract Within 1,000

What you'll learn

  • Estimate sums and differences within 1,000
  • Add and subtract using strategies and the standard algorithm
  • Solve single-step and multistep problems in context

Words to know

Sum —
the answer to an addition problem
Difference —
the answer to a subtraction problem
Estimate —
a close, reasonable answer using rounding
Regroup —
trade 10 in one place for 1 in the next place

Why it matters Adding and subtracting larger numbers lets us total scores, track savings, and figure out how much is left.

Worked examples

Model ItI do

Add 347 + 250 on an open number line.

Start at 347. Jump +100 to 447, +100 to 547, then +50 to 597. So 347 + 250 = 597.

Try It TogetherWe do

Estimate, then find 612 − 385.

Estimate: 600 − 400 = 200. Now subtract exactly, regrouping: 612 − 385 = 227. The answer is close to 200, so it is reasonable.

Now YouYou do

A library had 508 books and lent out 129. How many are left?

Decide the operation, estimate, then solve. Check your answer in the back.

Practice

Mastered 0 of 11

Warm-up

Ease in with the basics.

  1. 1.Find 234 + 152.

  2. 2.Find 480 - 130.

  3. 3.Estimate 210 + 190 to the nearest hundred.

On Level

The core Quick Check from the book.

  1. 1.Find 456 + 238.

  2. 2.Find 700 − 265.

  3. 3.Estimate 393 + 214 to the nearest hundred.

  4. 4.A team scored 245 points, then 178 more. How many in all?

  5. 5.True or false: 500 − 250 = 250.

Challenge

Stretch your thinking.

  1. 1.A store had 623 apples. It sold 148 in the morning and 96 in the afternoon. How many apples are left?

  2. 2.Find 802 - 367.

  3. 3.A school collected 356 cans, then 289 more. Estimate the total to the nearest hundred, then find the exact total.