← Subtract by rounding up and adding back lesson New set →

Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 874 · 40 questions
TalentJR

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

NameDateTime takenScore ___ / 40
  1. 1.524 − 297 =
  2. 2.479 − 299 =
  3. 3.830 − 379 =
  4. 4.819 − 298 =
  5. 5.602 − 519 =
  6. 6.904 − 629 =
  7. 7.819 − 599 =
  8. 8.357 − 199 =
  9. 9.363 − 117 =
  10. 10.579 − 547 =
  11. 11.342 − 177 =
  12. 12.816 − 697 =
  13. 13.645 − 598 =
  14. 14.700 − 239 =
  15. 15.713 − 608 =
  16. 16.949 − 598 =
  17. 17.993 − 499 =
  18. 18.679 − 399 =
  19. 19.925 − 799 =
  20. 20.393 − 189 =
  21. 21.891 − 238 =
  22. 22.457 − 227 =
  23. 23.610 − 559 =
  24. 24.868 − 797 =
  25. 25.175 − 127 =
  26. 26.750 − 499 =
  27. 27.474 − 307 =
  28. 28.520 − 198 =
  29. 29.735 − 438 =
  30. 30.667 − 399 =
  31. 31.836 − 299 =
  32. 32.969 − 198 =
  33. 33.764 − 299 =
  34. 34.546 − 498 =
  35. 35.967 − 799 =
  36. 36.967 − 697 =
  37. 37.713 − 407 =
  38. 38.595 − 297 =
  39. 39.750 − 207 =
  40. 40.953 − 797 =

Answer key

  1. 227
  2. 180
  3. 451
  4. 521
  5. 83
  6. 275
  7. 220
  8. 158
  9. 246
  10. 32
  11. 165
  12. 119
  13. 47
  14. 461
  15. 105
  16. 351
  17. 494
  18. 280
  19. 126
  20. 204
  21. 653
  22. 230
  23. 51
  24. 71
  25. 48
  26. 251
  27. 167
  28. 322
  29. 297
  30. 268
  31. 537
  32. 771
  33. 465
  34. 48
  35. 168
  36. 270
  37. 306
  38. 298
  39. 543
  40. 156

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths