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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 761 · 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. 1.489 + 511 =
  2. 2.672 − 247 =
  3. 3.736 + 541 =
  4. 4.294 + 519 =
  5. 5.624 − 499 =
  6. 6.955 − 168 =
  7. 7.529 + 121 =
  8. 8.630 + 309 =
  9. 9.194 + 283 =
  10. 10.649 + 545 =
  11. 11.515 + 334 =
  12. 12.651 + 299 =
  13. 13.783 − 281 =
  14. 14.494 − 316 =
  15. 15.484 − 219 =
  16. 16.438 − 279 =
  17. 17.837 − 202 =
  18. 18.259 + 331 =
  19. 19.407 + 324 =
  20. 20.422 − 218 =
  21. 21.136 + 449 =
  22. 22.565 − 282 =
  23. 23.244 + 194 =
  24. 24.169 + 119 =
  25. 25.148 + 434 =
  26. 26.931 − 474 =
  27. 27.139 + 423 =
  28. 28.577 − 264 =
  29. 29.513 − 134 =
  30. 30.676 + 359 =
  31. 31.474 + 229 =
  32. 32.561 − 214 =
  33. 33.783 + 263 =
  34. 34.579 − 129 =
  35. 35.572 + 588 =
  36. 36.518 − 279 =
  37. 37.439 − 327 =
  38. 38.827 − 622 =
  39. 39.702 − 118 =
  40. 40.658 − 195 =

Answer key

  1. 1000
  2. 425
  3. 1277
  4. 813
  5. 125
  6. 787
  7. 650
  8. 939
  9. 477
  10. 1194
  11. 849
  12. 950
  13. 502
  14. 178
  15. 265
  16. 159
  17. 635
  18. 590
  19. 731
  20. 204
  21. 585
  22. 283
  23. 438
  24. 288
  25. 582
  26. 457
  27. 562
  28. 313
  29. 379
  30. 1035
  31. 703
  32. 347
  33. 1046
  34. 450
  35. 1160
  36. 239
  37. 112
  38. 205
  39. 584
  40. 463

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