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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 533 · 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. 1.457 + 541 =
  2. 2.549 − 246 =
  3. 3.614 + 347 =
  4. 4.752 − 394 =
  5. 5.267 + 424 =
  6. 6.647 + 168 =
  7. 7.533 − 236 =
  8. 8.711 + 407 =
  9. 9.216 + 149 =
  10. 10.738 + 617 =
  11. 11.787 − 563 =
  12. 12.695 + 245 =
  13. 13.330 + 561 =
  14. 14.723 + 337 =
  15. 15.321 + 172 =
  16. 16.595 + 458 =
  17. 17.927 − 207 =
  18. 18.674 + 149 =
  19. 19.490 − 269 =
  20. 20.562 − 319 =
  21. 21.781 − 216 =
  22. 22.385 + 455 =
  23. 23.499 − 113 =
  24. 24.213 + 417 =
  25. 25.440 + 429 =
  26. 26.296 + 282 =
  27. 27.418 − 144 =
  28. 28.553 − 167 =
  29. 29.787 − 215 =
  30. 30.657 + 621 =
  31. 31.616 + 519 =
  32. 32.621 + 511 =
  33. 33.676 + 681 =
  34. 34.482 + 161 =
  35. 35.150 + 244 =
  36. 36.803 − 569 =
  37. 37.246 + 193 =
  38. 38.553 − 304 =
  39. 39.559 + 116 =
  40. 40.285 + 546 =

Answer key

  1. 998
  2. 303
  3. 961
  4. 358
  5. 691
  6. 815
  7. 297
  8. 1118
  9. 365
  10. 1355
  11. 224
  12. 940
  13. 891
  14. 1060
  15. 493
  16. 1053
  17. 720
  18. 823
  19. 221
  20. 243
  21. 565
  22. 840
  23. 386
  24. 630
  25. 869
  26. 578
  27. 274
  28. 386
  29. 572
  30. 1278
  31. 1135
  32. 1132
  33. 1357
  34. 643
  35. 394
  36. 234
  37. 439
  38. 249
  39. 675
  40. 831

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