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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 743 · 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, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  2. 2.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?
  3. 3.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  4. 4.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  5. 5.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  7. 7.A leapfrog list starts 8, 8 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, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  9. 9.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?
  10. 10.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  12. 12.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?
  13. 13.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  14. 14.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  17. 17.A leapfrog list starts 5, 4 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 4, 3 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 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  21. 21.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  22. 22.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  25. 25.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  26. 26.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  28. 28.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  30. 30.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  31. 31.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  33. 33.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  34. 34.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?
  35. 35.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  37. 37.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  38. 38.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  39. 39.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?
  40. 40.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =

Answer key

  1. 880
  2. 341
  3. 803
  4. 682
  5. 473
  6. 968
  7. 1144
  8. 308
  9. 715
  10. 1089
  11. 1067
  12. 649
  13. 429
  14. 935
  15. 517
  16. 418
  17. 627
  18. 484
  19. 253
  20. 517
  21. 1177
  22. 957
  23. 858
  24. 759
  25. 583
  26. 572
  27. 825
  28. 418
  29. 1111
  30. 660
  31. 539
  32. 407
  33. 341
  34. 616
  35. 319
  36. 374
  37. 495
  38. 913
  39. 1023
  40. 286

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