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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 504 · 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. 1.676 + 555 =
  2. 2.737 + 271 =
  3. 3.632 + 451 =
  4. 4.545 − 181 =
  5. 5.736 + 299 =
  6. 6.701 + 207 =
  7. 7.400 + 533 =
  8. 8.766 − 511 =
  9. 9.580 − 393 =
  10. 10.692 + 331 =
  11. 11.760 − 181 =
  12. 12.796 − 154 =
  13. 13.379 + 191 =
  14. 14.136 + 121 =
  15. 15.587 + 113 =
  16. 16.500 − 226 =
  17. 17.637 + 139 =
  18. 18.672 + 581 =
  19. 19.679 − 209 =
  20. 20.445 − 223 =
  21. 21.455 − 259 =
  22. 22.548 − 145 =
  23. 23.967 − 748 =
  24. 24.698 − 233 =
  25. 25.308 + 153 =
  26. 26.420 − 128 =
  27. 27.323 + 331 =
  28. 28.516 + 207 =
  29. 29.133 + 143 =
  30. 30.621 + 252 =
  31. 31.509 + 351 =
  32. 32.415 + 529 =
  33. 33.150 + 674 =
  34. 34.701 − 245 =
  35. 35.784 − 222 =
  36. 36.585 + 258 =
  37. 37.399 + 175 =
  38. 38.438 + 312 =
  39. 39.459 − 202 =
  40. 40.736 − 251 =

Answer key

  1. 1231
  2. 1008
  3. 1083
  4. 364
  5. 1035
  6. 908
  7. 933
  8. 255
  9. 187
  10. 1023
  11. 579
  12. 642
  13. 570
  14. 257
  15. 700
  16. 274
  17. 776
  18. 1253
  19. 470
  20. 222
  21. 196
  22. 403
  23. 219
  24. 465
  25. 461
  26. 292
  27. 654
  28. 723
  29. 276
  30. 873
  31. 860
  32. 944
  33. 824
  34. 456
  35. 562
  36. 843
  37. 574
  38. 750
  39. 257
  40. 485

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