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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 96 · 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. 1.145 + 202 =
  2. 2.318 + 215 =
  3. 3.962 − 771 =
  4. 4.568 + 232 =
  5. 5.544 + 252 =
  6. 6.577 − 427 =
  7. 7.201 + 177 =
  8. 8.703 + 293 =
  9. 9.148 + 676 =
  10. 10.637 − 192 =
  11. 11.633 − 138 =
  12. 12.907 − 295 =
  13. 13.982 − 811 =
  14. 14.720 + 116 =
  15. 15.508 − 319 =
  16. 16.657 − 251 =
  17. 17.298 + 501 =
  18. 18.690 + 436 =
  19. 19.727 + 324 =
  20. 20.601 − 464 =
  21. 21.758 − 125 =
  22. 22.755 − 296 =
  23. 23.483 + 327 =
  24. 24.449 − 258 =
  25. 25.544 + 231 =
  26. 26.454 + 526 =
  27. 27.234 + 163 =
  28. 28.245 + 525 =
  29. 29.591 − 128 =
  30. 30.688 − 451 =
  31. 31.673 − 188 =
  32. 32.235 + 393 =
  33. 33.296 + 569 =
  34. 34.151 + 606 =
  35. 35.503 − 298 =
  36. 36.850 − 715 =
  37. 37.787 + 446 =
  38. 38.442 + 413 =
  39. 39.970 − 754 =
  40. 40.254 + 677 =

Answer key

  1. 347
  2. 533
  3. 191
  4. 800
  5. 796
  6. 150
  7. 378
  8. 996
  9. 824
  10. 445
  11. 495
  12. 612
  13. 171
  14. 836
  15. 189
  16. 406
  17. 799
  18. 1126
  19. 1051
  20. 137
  21. 633
  22. 459
  23. 810
  24. 191
  25. 775
  26. 980
  27. 397
  28. 770
  29. 463
  30. 237
  31. 485
  32. 628
  33. 865
  34. 757
  35. 205
  36. 135
  37. 1233
  38. 855
  39. 216
  40. 931

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