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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 235 · 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. 1.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  2. 2.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  4. 4.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  7. 7.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  8. 8.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?
  9. 9.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  11. 11.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  13. 13.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?
  14. 14.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  15. 15.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  16. 16.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  17. 17.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?
  18. 18.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.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?
  20. 20.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?
  21. 21.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  22. 22.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  23. 23.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  25. 25.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  28. 28.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?
  29. 29.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?
  30. 30.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  33. 33.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  35. 35.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  36. 36.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?
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  38. 38.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?

Answer key

  1. 1111
  2. 1287
  3. 517
  4. 803
  5. 869
  6. 1122
  7. 1144
  8. 363
  9. 495
  10. 1232
  11. 1089
  12. 473
  13. 451
  14. 286
  15. 704
  16. 594
  17. 594
  18. 517
  19. 143
  20. 407
  21. 748
  22. 627
  23. 825
  24. 825
  25. 341
  26. 396
  27. 231
  28. 682
  29. 231
  30. 979
  31. 506
  32. 781
  33. 605
  34. 715
  35. 374
  36. 847
  37. 341
  38. 484
  39. 704
  40. 1023

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