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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 150 · 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): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  4. 4.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  5. 5.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  6. 6.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  7. 7.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?
  8. 8.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  10. 10.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  13. 13.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  14. 14.A leapfrog list starts 2, 3 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): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  16. 16.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  17. 17.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  19. 19.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  20. 20.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  21. 21.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  24. 24.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?
  25. 25.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.A leapfrog list starts 4, 6 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 3, 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 8, 4 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 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.A leapfrog list starts 2, 8 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 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  39. 39.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  40. 40.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?

Answer key

  1. 605
  2. 1122
  3. 1199
  4. 517
  5. 605
  6. 748
  7. 759
  8. 253
  9. 484
  10. 968
  11. 561
  12. 594
  13. 198
  14. 374
  15. 550
  16. 561
  17. 682
  18. 1012
  19. 1122
  20. 539
  21. 693
  22. 198
  23. 286
  24. 495
  25. 1199
  26. 759
  27. 1089
  28. 726
  29. 748
  30. 869
  31. 792
  32. 462
  33. 517
  34. 814
  35. 1067
  36. 1023
  37. 583
  38. 583
  39. 814
  40. 1177

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