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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 62 · 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.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?
  2. 2.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  3. 3.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  4. 4.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?
  5. 5.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  6. 6.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  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. 8.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  9. 9.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  10. 10.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?
  11. 11.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  12. 12.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  13. 13.A leapfrog list starts 1, 9 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): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  15. 15.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  16. 16.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?
  17. 17.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  18. 18.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  20. 20.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  21. 21.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?
  22. 22.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  23. 23.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  24. 24.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  27. 27.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  28. 28.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  30. 30.A leapfrog list starts 8, 4 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 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  34. 34.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?
  35. 35.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  37. 37.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?
  38. 38.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?
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?

Answer key

  1. 902
  2. 616
  3. 858
  4. 748
  5. 704
  6. 1177
  7. 682
  8. 583
  9. 803
  10. 627
  11. 671
  12. 253
  13. 847
  14. 902
  15. 528
  16. 671
  17. 473
  18. 484
  19. 286
  20. 671
  21. 847
  22. 198
  23. 374
  24. 583
  25. 539
  26. 693
  27. 682
  28. 539
  29. 495
  30. 792
  31. 341
  32. 605
  33. 671
  34. 759
  35. 1122
  36. 462
  37. 319
  38. 649
  39. 1144
  40. 671

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