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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 891 · 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, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  2. 2.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?
  3. 3.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?
  4. 4.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  5. 5.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  6. 6.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  7. 7.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  8. 8.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  9. 9.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  10. 10.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.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?
  12. 12.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  13. 13.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  14. 14.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  15. 15.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  16. 16.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  17. 17.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?
  18. 18.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  19. 19.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  21. 21.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  22. 22.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  23. 23.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?
  24. 24.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  25. 25.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?
  26. 26.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  29. 29.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  30. 30.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  32. 32.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  33. 33.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  35. 35.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  36. 36.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  37. 37.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?
  38. 38.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 517
  2. 638
  3. 759
  4. 429
  5. 847
  6. 737
  7. 286
  8. 759
  9. 627
  10. 880
  11. 605
  12. 583
  13. 638
  14. 1012
  15. 781
  16. 561
  17. 143
  18. 957
  19. 759
  20. 451
  21. 605
  22. 1001
  23. 715
  24. 539
  25. 561
  26. 308
  27. 253
  28. 1001
  29. 253
  30. 957
  31. 847
  32. 715
  33. 198
  34. 1034
  35. 1177
  36. 726
  37. 726
  38. 484
  39. 198
  40. 484

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