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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 734 · 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. 1.762 − 386 =
  2. 2.778 + 676 =
  3. 3.763 − 593 =
  4. 4.807 − 243 =
  5. 5.552 − 423 =
  6. 6.573 + 195 =
  7. 7.825 − 254 =
  8. 8.857 − 354 =
  9. 9.318 + 419 =
  10. 10.462 − 146 =
  11. 11.476 − 234 =
  12. 12.265 + 502 =
  13. 13.590 + 337 =
  14. 14.762 + 432 =
  15. 15.890 − 592 =
  16. 16.480 − 356 =
  17. 17.547 + 146 =
  18. 18.544 − 311 =
  19. 19.688 + 125 =
  20. 20.151 + 541 =
  21. 21.312 + 526 =
  22. 22.567 − 209 =
  23. 23.460 + 363 =
  24. 24.261 + 585 =
  25. 25.757 − 373 =
  26. 26.830 − 681 =
  27. 27.431 + 257 =
  28. 28.945 − 666 =
  29. 29.810 − 649 =
  30. 30.409 + 252 =
  31. 31.601 + 181 =
  32. 32.216 + 119 =
  33. 33.786 + 565 =
  34. 34.321 + 689 =
  35. 35.402 + 144 =
  36. 36.740 + 155 =
  37. 37.597 − 123 =
  38. 38.712 + 124 =
  39. 39.484 − 148 =
  40. 40.654 + 159 =

Answer key

  1. 376
  2. 1454
  3. 170
  4. 564
  5. 129
  6. 768
  7. 571
  8. 503
  9. 737
  10. 316
  11. 242
  12. 767
  13. 927
  14. 1194
  15. 298
  16. 124
  17. 693
  18. 233
  19. 813
  20. 692
  21. 838
  22. 358
  23. 823
  24. 846
  25. 384
  26. 149
  27. 688
  28. 279
  29. 161
  30. 661
  31. 782
  32. 335
  33. 1351
  34. 1010
  35. 546
  36. 895
  37. 474
  38. 836
  39. 336
  40. 813

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