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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 541 · 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. 1.623 + 632 =
  2. 2.419 − 186 =
  3. 3.945 − 202 =
  4. 4.844 − 519 =
  5. 5.454 − 335 =
  6. 6.465 − 225 =
  7. 7.516 + 359 =
  8. 8.561 − 231 =
  9. 9.776 + 504 =
  10. 10.718 − 181 =
  11. 11.242 + 252 =
  12. 12.253 + 373 =
  13. 13.624 − 158 =
  14. 14.535 − 339 =
  15. 15.137 + 261 =
  16. 16.761 + 442 =
  17. 17.771 − 644 =
  18. 18.412 − 119 =
  19. 19.787 − 425 =
  20. 20.638 + 362 =
  21. 21.787 − 381 =
  22. 22.220 + 565 =
  23. 23.614 − 354 =
  24. 24.473 − 247 =
  25. 25.954 − 639 =
  26. 26.570 − 178 =
  27. 27.589 + 308 =
  28. 28.648 − 176 =
  29. 29.678 + 572 =
  30. 30.419 − 141 =
  31. 31.153 + 323 =
  32. 32.687 + 298 =
  33. 33.158 + 578 =
  34. 34.457 + 598 =
  35. 35.600 − 481 =
  36. 36.914 − 346 =
  37. 37.747 + 612 =
  38. 38.742 − 325 =
  39. 39.470 + 239 =
  40. 40.234 + 269 =

Answer key

  1. 1255
  2. 233
  3. 743
  4. 325
  5. 119
  6. 240
  7. 875
  8. 330
  9. 1280
  10. 537
  11. 494
  12. 626
  13. 466
  14. 196
  15. 398
  16. 1203
  17. 127
  18. 293
  19. 362
  20. 1000
  21. 406
  22. 785
  23. 260
  24. 226
  25. 315
  26. 392
  27. 897
  28. 472
  29. 1250
  30. 278
  31. 476
  32. 985
  33. 736
  34. 1055
  35. 119
  36. 568
  37. 1359
  38. 417
  39. 709
  40. 503

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