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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 176 · 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. 1.537 − 147 =
  2. 2.646 − 492 =
  3. 3.847 − 427 =
  4. 4.229 + 267 =
  5. 5.712 + 487 =
  6. 6.545 + 324 =
  7. 7.779 − 202 =
  8. 8.975 − 328 =
  9. 9.505 − 154 =
  10. 10.589 + 561 =
  11. 11.644 + 271 =
  12. 12.511 + 585 =
  13. 13.902 − 253 =
  14. 14.707 + 414 =
  15. 15.420 + 151 =
  16. 16.671 + 175 =
  17. 17.499 − 153 =
  18. 18.375 + 655 =
  19. 19.674 − 245 =
  20. 20.418 − 129 =
  21. 21.984 − 272 =
  22. 22.298 + 388 =
  23. 23.725 + 305 =
  24. 24.799 − 182 =
  25. 25.681 − 298 =
  26. 26.783 + 501 =
  27. 27.436 + 528 =
  28. 28.507 + 269 =
  29. 29.280 + 507 =
  30. 30.604 − 313 =
  31. 31.577 + 164 =
  32. 32.484 − 234 =
  33. 33.503 − 131 =
  34. 34.483 − 351 =
  35. 35.508 + 559 =
  36. 36.412 − 288 =
  37. 37.750 − 516 =
  38. 38.842 − 321 =
  39. 39.570 − 343 =
  40. 40.454 − 221 =

Answer key

  1. 390
  2. 154
  3. 420
  4. 496
  5. 1199
  6. 869
  7. 577
  8. 647
  9. 351
  10. 1150
  11. 915
  12. 1096
  13. 649
  14. 1121
  15. 571
  16. 846
  17. 346
  18. 1030
  19. 429
  20. 289
  21. 712
  22. 686
  23. 1030
  24. 617
  25. 383
  26. 1284
  27. 964
  28. 776
  29. 787
  30. 291
  31. 741
  32. 250
  33. 372
  34. 132
  35. 1067
  36. 124
  37. 234
  38. 521
  39. 227
  40. 233

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