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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 386 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.626 + 678 =
  2. 2.497 + 361 =
  3. 3.541 − 258 =
  4. 4.865 − 188 =
  5. 5.507 − 344 =
  6. 6.466 − 296 =
  7. 7.518 + 198 =
  8. 8.277 + 266 =
  9. 9.449 − 181 =
  10. 10.399 + 368 =
  11. 11.466 + 205 =
  12. 12.958 − 321 =
  13. 13.450 + 125 =
  14. 14.483 − 307 =
  15. 15.833 − 172 =
  16. 16.555 − 431 =
  17. 17.662 + 179 =
  18. 18.243 + 604 =
  19. 19.703 + 375 =
  20. 20.376 + 501 =
  21. 21.647 − 301 =
  22. 22.149 + 168 =
  23. 23.781 − 501 =
  24. 24.468 − 211 =
  25. 25.239 + 554 =
  26. 26.580 − 447 =
  27. 27.504 + 437 =
  28. 28.283 + 189 =
  29. 29.253 + 359 =
  30. 30.664 − 284 =
  31. 31.509 − 225 =
  32. 32.623 − 445 =
  33. 33.322 + 351 =
  34. 34.518 + 659 =
  35. 35.443 + 146 =
  36. 36.630 − 294 =
  37. 37.648 + 234 =
  38. 38.504 + 303 =
  39. 39.401 + 679 =
  40. 40.410 + 391 =

Answer key

  1. 1304
  2. 858
  3. 283
  4. 677
  5. 163
  6. 170
  7. 716
  8. 543
  9. 268
  10. 767
  11. 671
  12. 637
  13. 575
  14. 176
  15. 661
  16. 124
  17. 841
  18. 847
  19. 1078
  20. 877
  21. 346
  22. 317
  23. 280
  24. 257
  25. 793
  26. 133
  27. 941
  28. 472
  29. 612
  30. 380
  31. 284
  32. 178
  33. 673
  34. 1177
  35. 589
  36. 336
  37. 882
  38. 807
  39. 1080
  40. 801

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