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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 946 · 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. 1.293 + 385 =
  2. 2.320 + 578 =
  3. 3.270 + 258 =
  4. 4.155 + 644 =
  5. 5.243 + 468 =
  6. 6.682 + 572 =
  7. 7.807 − 523 =
  8. 8.890 − 536 =
  9. 9.752 − 321 =
  10. 10.162 + 651 =
  11. 11.439 − 262 =
  12. 12.224 + 689 =
  13. 13.746 + 258 =
  14. 14.449 + 623 =
  15. 15.706 − 126 =
  16. 16.260 + 669 =
  17. 17.765 − 326 =
  18. 18.219 + 341 =
  19. 19.687 − 459 =
  20. 20.646 + 181 =
  21. 21.977 − 548 =
  22. 22.295 + 164 =
  23. 23.306 + 244 =
  24. 24.386 + 606 =
  25. 25.491 − 304 =
  26. 26.339 + 651 =
  27. 27.129 + 488 =
  28. 28.596 + 606 =
  29. 29.826 − 179 =
  30. 30.275 + 452 =
  31. 31.948 − 372 =
  32. 32.571 − 306 =
  33. 33.442 − 324 =
  34. 34.142 + 349 =
  35. 35.616 − 181 =
  36. 36.629 + 629 =
  37. 37.451 + 406 =
  38. 38.680 + 226 =
  39. 39.965 − 828 =
  40. 40.486 − 158 =

Answer key

  1. 678
  2. 898
  3. 528
  4. 799
  5. 711
  6. 1254
  7. 284
  8. 354
  9. 431
  10. 813
  11. 177
  12. 913
  13. 1004
  14. 1072
  15. 580
  16. 929
  17. 439
  18. 560
  19. 228
  20. 827
  21. 429
  22. 459
  23. 550
  24. 992
  25. 187
  26. 990
  27. 617
  28. 1202
  29. 647
  30. 727
  31. 576
  32. 265
  33. 118
  34. 491
  35. 435
  36. 1258
  37. 857
  38. 906
  39. 137
  40. 328

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