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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 251 · 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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  5. 5.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  6. 6.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?
  7. 7.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  8. 8.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  9. 9.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  10. 10.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  11. 11.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?
  12. 12.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?
  13. 13.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?
  14. 14.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  16. 16.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?
  17. 17.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?
  18. 18.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  19. 19.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?
  20. 20.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  21. 21.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  22. 22.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  23. 23.A leapfrog list starts 6, 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 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  26. 26.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  28. 28.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?
  29. 29.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  31. 31.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  32. 32.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  33. 33.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  35. 35.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  36. 36.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  37. 37.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?
  38. 38.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  40. 40.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =

Answer key

  1. 616
  2. 572
  3. 528
  4. 616
  5. 429
  6. 759
  7. 902
  8. 418
  9. 462
  10. 858
  11. 231
  12. 671
  13. 715
  14. 891
  15. 550
  16. 638
  17. 693
  18. 506
  19. 253
  20. 913
  21. 726
  22. 539
  23. 858
  24. 759
  25. 484
  26. 693
  27. 880
  28. 649
  29. 814
  30. 814
  31. 396
  32. 627
  33. 286
  34. 506
  35. 308
  36. 1001
  37. 1023
  38. 660
  39. 143
  40. 253

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