Unit 3 Answer Key PDF
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This document contains math practice problems for addition and subtraction, including estimating sums and differences, and solving multi-digit problems. The questions are presented in clear format with instructions.
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Unit 3 Answer Key **Part 1: Estimate Sums and Differences** **Hint:** Round each number to the nearest ten or hundred before solving. 1. **Estimate the following sums:**\ a) **345 + 267 ≈ 350 + 270 = 620**\ b) **728 + 194 ≈ 730 + 190 = 920**\ c) **563 + 325 ≈ 560 + 330 = 890** 2. *...
Unit 3 Answer Key **Part 1: Estimate Sums and Differences** **Hint:** Round each number to the nearest ten or hundred before solving. 1. **Estimate the following sums:**\ a) **345 + 267 ≈ 350 + 270 = 620**\ b) **728 + 194 ≈ 730 + 190 = 920**\ c) **563 + 325 ≈ 560 + 330 = 890** 2. **Estimate the following differences:**\ a) **823 - 451 ≈ 820 - 450 = 370**\ b) **679 - 214 ≈ 680 - 210 = 470**\ c) **910 - 375 ≈ 910 - 380 = 530** **Part 2: Strategies to Add Multi-Digit Numbers** **Solve using strategies like base-ten, expanded form, or a number line.** 3. **Solve:**\ a) **486 + 239 = 725**\ b) **729 + 354 = 1,083**\ c) **625 + 412 = 1,037** **Part 3: Addition Algorithm Without Regrouping** **Direct addition without regrouping needed.** 4. **Solve:**\ a) **234 + 143 = 377**\ b) **512 + 236 = 748**\ c) **421 + 308 = 729** **Part 4: Addition Algorithm with Regrouping** **Addition where digits require regrouping.** 5. **Solve:**\ a) **368 + 457 = 825**\ b) **589 + 376 = 965**\ c) **742 + 295 = 1,037** **Part 5: Strategies to Subtract Multi-Digit Numbers** **Solve using strategies like base-ten, expanded form, or a number line.** 6. **Solve:**\ a) **835 - 248 = 587**\ b) **742 - 316 = 426**\ c) **609 - 172 = 437** **Part 6: Subtraction Algorithm Without Regrouping** **Direct subtraction without regrouping needed.** 7. **Solve:**\ a) **543 - 231 = 312**\ b) **604 - 302 = 302**\ c) **785 - 453 = 332** **Part 7: Subtraction Algorithm with Regrouping** **Subtraction where regrouping is required.** 8. **Solve:**\ a) **843 - 268 = 575**\ b) **650 - 475 = 175**\ c) **900 - 381 = 519** **Part 8: Addition and Subtraction Word Problems** **Use the CUBES strategy (Circle, Underline, Box, Eliminate, Solve).** 9. **Addition Word Problems:**\ a) **312 + 198 = 510 animals**\ b) **483 + 269 = 752 books** 10. **Subtraction Word Problems:**\ a) **587 - 246 = 341 shells**\ b) **736 - 298 = 438 toys**
