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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 925 · 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. 1.789 − 123 =
  2. 2.270 + 597 =
  3. 3.444 − 225 =
  4. 4.514 − 389 =
  5. 5.217 + 236 =
  6. 6.601 + 408 =
  7. 7.247 + 328 =
  8. 8.275 + 358 =
  9. 9.766 − 558 =
  10. 10.709 − 416 =
  11. 11.253 + 371 =
  12. 12.620 − 455 =
  13. 13.294 + 606 =
  14. 14.685 + 235 =
  15. 15.838 − 208 =
  16. 16.849 − 515 =
  17. 17.703 + 588 =
  18. 18.701 − 232 =
  19. 19.753 + 384 =
  20. 20.606 − 428 =
  21. 21.234 + 652 =
  22. 22.265 + 305 =
  23. 23.351 + 481 =
  24. 24.764 − 558 =
  25. 25.544 + 417 =
  26. 26.487 − 347 =
  27. 27.485 + 441 =
  28. 28.518 + 232 =
  29. 29.436 + 344 =
  30. 30.796 − 116 =
  31. 31.667 + 481 =
  32. 32.435 − 155 =
  33. 33.578 + 679 =
  34. 34.459 + 289 =
  35. 35.188 + 609 =
  36. 36.816 − 421 =
  37. 37.831 − 179 =
  38. 38.593 + 584 =
  39. 39.615 − 177 =
  40. 40.246 + 392 =

Answer key

  1. 666
  2. 867
  3. 219
  4. 125
  5. 453
  6. 1009
  7. 575
  8. 633
  9. 208
  10. 293
  11. 624
  12. 165
  13. 900
  14. 920
  15. 630
  16. 334
  17. 1291
  18. 469
  19. 1137
  20. 178
  21. 886
  22. 570
  23. 832
  24. 206
  25. 961
  26. 140
  27. 926
  28. 750
  29. 780
  30. 680
  31. 1148
  32. 280
  33. 1257
  34. 748
  35. 797
  36. 395
  37. 652
  38. 1177
  39. 438
  40. 638

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