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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 427 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  3. 3.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  4. 4.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  5. 5.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  6. 6.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  9. 9.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  11. 11.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  12. 12.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  13. 13.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  15. 15.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  17. 17.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  18. 18.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  19. 19.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  20. 20.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  22. 22.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  23. 23.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  26. 26.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  29. 29.A leapfrog list starts 8, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.A leapfrog list starts 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  32. 32.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  35. 35.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  37. 37.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?

Answer key

  1. 649
  2. 704
  3. 935
  4. 946
  5. 979
  6. 231
  7. 429
  8. 396
  9. 1144
  10. 253
  11. 781
  12. 418
  13. 902
  14. 726
  15. 957
  16. 1287
  17. 495
  18. 506
  19. 792
  20. 594
  21. 880
  22. 627
  23. 748
  24. 451
  25. 1232
  26. 814
  27. 583
  28. 847
  29. 1056
  30. 671
  31. 594
  32. 253
  33. 561
  34. 726
  35. 1177
  36. 308
  37. 715
  38. 814
  39. 143
  40. 319

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