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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 477 · 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): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  2. 2.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  3. 3.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  4. 4.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  6. 6.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  7. 7.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  8. 8.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?
  9. 9.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  10. 10.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  12. 12.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  13. 13.A leapfrog list starts 7, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  15. 15.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  16. 16.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  20. 20.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  23. 23.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  24. 24.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  26. 26.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  28. 28.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  29. 29.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  30. 30.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  32. 32.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  33. 33.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  35. 35.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  36. 36.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  38. 38.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?

Answer key

  1. 726
  2. 473
  3. 198
  4. 759
  5. 1012
  6. 484
  7. 682
  8. 1056
  9. 902
  10. 605
  11. 759
  12. 627
  13. 737
  14. 946
  15. 374
  16. 759
  17. 605
  18. 1232
  19. 363
  20. 616
  21. 693
  22. 792
  23. 858
  24. 407
  25. 902
  26. 649
  27. 847
  28. 935
  29. 319
  30. 638
  31. 396
  32. 1287
  33. 1034
  34. 660
  35. 1177
  36. 638
  37. 836
  38. 814
  39. 902
  40. 803

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