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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 235 · 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. 1.334 + 544 =
  2. 2.538 − 191 =
  3. 3.530 − 325 =
  4. 4.137 + 302 =
  5. 5.626 − 127 =
  6. 6.213 + 624 =
  7. 7.784 − 343 =
  8. 8.585 − 392 =
  9. 9.875 − 202 =
  10. 10.797 − 647 =
  11. 11.399 + 554 =
  12. 12.582 − 113 =
  13. 13.813 − 704 =
  14. 14.192 + 567 =
  15. 15.368 + 591 =
  16. 16.270 + 212 =
  17. 17.402 + 254 =
  18. 18.605 + 345 =
  19. 19.497 + 512 =
  20. 20.952 − 396 =
  21. 21.578 − 215 =
  22. 22.324 + 418 =
  23. 23.731 − 114 =
  24. 24.598 + 158 =
  25. 25.400 + 296 =
  26. 26.830 − 341 =
  27. 27.650 + 582 =
  28. 28.448 + 671 =
  29. 29.602 + 331 =
  30. 30.347 + 493 =
  31. 31.484 + 113 =
  32. 32.654 + 353 =
  33. 33.554 + 517 =
  34. 34.577 + 257 =
  35. 35.846 − 389 =
  36. 36.502 − 283 =
  37. 37.515 − 113 =
  38. 38.431 − 256 =
  39. 39.476 + 327 =
  40. 40.530 + 649 =

Answer key

  1. 878
  2. 347
  3. 205
  4. 439
  5. 499
  6. 837
  7. 441
  8. 193
  9. 673
  10. 150
  11. 953
  12. 469
  13. 109
  14. 759
  15. 959
  16. 482
  17. 656
  18. 950
  19. 1009
  20. 556
  21. 363
  22. 742
  23. 617
  24. 756
  25. 696
  26. 489
  27. 1232
  28. 1119
  29. 933
  30. 840
  31. 597
  32. 1007
  33. 1071
  34. 834
  35. 457
  36. 219
  37. 402
  38. 175
  39. 803
  40. 1179

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