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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 118 · 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. 1.242 + 396 =
  2. 2.257 + 276 =
  3. 3.499 − 271 =
  4. 4.460 + 154 =
  5. 5.510 − 263 =
  6. 6.750 − 252 =
  7. 7.206 + 372 =
  8. 8.628 + 627 =
  9. 9.502 + 663 =
  10. 10.783 − 572 =
  11. 11.846 − 385 =
  12. 12.512 − 275 =
  13. 13.624 − 193 =
  14. 14.454 + 589 =
  15. 15.246 + 264 =
  16. 16.818 − 179 =
  17. 17.169 + 317 =
  18. 18.425 − 113 =
  19. 19.532 + 131 =
  20. 20.652 − 132 =
  21. 21.872 − 242 =
  22. 22.440 − 178 =
  23. 23.371 + 463 =
  24. 24.805 − 245 =
  25. 25.737 − 346 =
  26. 26.778 − 558 =
  27. 27.532 − 143 =
  28. 28.547 − 174 =
  29. 29.785 + 239 =
  30. 30.948 − 395 =
  31. 31.161 + 588 =
  32. 32.503 + 401 =
  33. 33.383 + 291 =
  34. 34.450 + 513 =
  35. 35.732 + 641 =
  36. 36.689 + 642 =
  37. 37.560 − 135 =
  38. 38.170 + 535 =
  39. 39.749 − 389 =
  40. 40.972 − 821 =

Answer key

  1. 638
  2. 533
  3. 228
  4. 614
  5. 247
  6. 498
  7. 578
  8. 1255
  9. 1165
  10. 211
  11. 461
  12. 237
  13. 431
  14. 1043
  15. 510
  16. 639
  17. 486
  18. 312
  19. 663
  20. 520
  21. 630
  22. 262
  23. 834
  24. 560
  25. 391
  26. 220
  27. 389
  28. 373
  29. 1024
  30. 553
  31. 749
  32. 904
  33. 674
  34. 963
  35. 1373
  36. 1331
  37. 425
  38. 705
  39. 360
  40. 151

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